Add the title "More information " to the article (#22288)
This commit is contained in:
Muralidharan Sekar
Tom
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---
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---
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title: Conditional Statements
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title: Conditional Statements
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---
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---
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# Conditional Statements in C
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# Conditional Statements in C
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Conditional Statements are also known as Branching Statements. They are so called because the program chooses to follow one branch or another.
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Conditional Statements are also known as Branching Statements. They are so called because the program chooses to follow one branch or another.
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## 1. if statement
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## 1. if statement
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This is the most simple form of the conditional statements. It consists of a Boolean expression followed by one or more statements. If the Boolean expression evaluates to **true**, then the block of code inside the 'if' statement will be executed. If the Boolean expression evaluates to **false**, then the first set of code after the end of the 'if' statement (after the closing curly brace) will be executed.
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This is the most simple form of the conditional statements. It consists of a Boolean expression followed by one or more statements. If the Boolean expression evaluates to **true**, then the block of code inside the 'if' statement will be executed. If the Boolean expression evaluates to **false**, then the first set of code after the end of the 'if' statement (after the closing curly brace) will be executed.
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C programming language **_assumes any non-zero and non-null values as true_** and if it is **_either zero or null, then it is assumed as false_** value.
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C programming language **_assumes any non-zero and non-null values as true_** and if it is **_either zero or null, then it is assumed as false_** value.
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#### Syntax
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#### Syntax
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```C
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```C
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if(boolean_expression)
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if(boolean_expression)
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{
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{
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//Block of Statements executed when boolean_expression is true
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//Block of Statements executed when boolean_expression is true
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}
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}
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```
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```
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#### Example
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```C
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#### Example
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int a = 100;
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```C
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if(a < 200)
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int a = 100;
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{
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if(a < 200)
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printf("a is less than 200\n" );
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{
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}
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printf("a is less than 200\n" );
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```
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}
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#### Result
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```
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`a is less than 200`
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#### Result
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`a is less than 200`
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## 2. if...else statement
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## 2. if...else statement
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If the Boolean expression evaluates to **true**, then the if block will be executed, otherwise, the else block will be executed.
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If the Boolean expression evaluates to **true**, then the if block will be executed, otherwise, the else block will be executed.
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#### Syntax
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```C
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#### Syntax
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if(boolean_expression)
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```C
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{
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if(boolean_expression)
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//Block of Statements executed when boolean_expression is true
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{
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}
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//Block of Statements executed when boolean_expression is true
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else
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}
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{
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else
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//Block of Statements executed when boolean_expression is false
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{
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}
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//Block of Statements executed when boolean_expression is false
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```
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}
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#### Example
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```
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```C
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int a = 300;
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#### Example
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if(a < 200)
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```C
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{
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int a = 300;
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printf("a is less than 200\n");
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if(a < 200)
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}
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{
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else
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printf("a is less than 200\n");
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{
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}
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printf("a is more than 200\n");
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else
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}
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{
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```
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printf("a is more than 200\n");
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#### Result
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}
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```
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`a is more than 200`
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#### Result
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## 3. if...else if...else statement
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`a is more than 200`
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When using if...else if..else statements, there are few points to keep in mind -
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- An **if** can have **zero or one else**'s and it **must come after any else if**'s.
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## 3. if...else if...else statement
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- An **if** can have **zero to many else if**'s and they **must come before the else**.
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When using if...else if..else statements, there are few points to keep in mind -
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- Once an **else if** succeeds, none of the remaining else if's or else's will be tested.
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- An **if** can have **zero or one else**'s and it **must come after any else if**'s.
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- An **if** can have **zero to many else if**'s and they **must come before the else**.
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#### Syntax
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- Once an **else if** succeeds, none of the remaining else if's or else's will be tested.
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```C
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if(boolean_expression_1)
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#### Syntax
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{
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```C
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//Block of Statements executed when boolean_expression_1 is true
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if(boolean_expression_1)
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}
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{
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else if(boolean_expression_2)
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//Block of Statements executed when boolean_expression_1 is true
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{
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}
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//Block of Statements executed when boolean_expression_1 is false and boolean_expression_2 is true
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else if(boolean_expression_2)
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}
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{
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else if(boolean_expression_3)
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//Block of Statements executed when boolean_expression_1 is false and boolean_expression_2 is true
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{
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}
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//Block of Statements executed when both boolean_expression_1 and boolean_expression_2 are false and boolean_expression_3 is true
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else if(boolean_expression_3)
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}
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{
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else
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//Block of Statements executed when both boolean_expression_1 and boolean_expression_2 are false and boolean_expression_3 is true
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{
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}
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//Block of Statements executed when all boolean_expression_1, boolean_expression_2 and boolean_expression_3 are false
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else
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}
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{
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```
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//Block of Statements executed when all boolean_expression_1, boolean_expression_2 and boolean_expression_3 are false
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#### Example
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}
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```C
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```
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int a = 300;
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if(a == 100)
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#### Example
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{
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```C
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printf("a is equal to 100\n");
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int a = 300;
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}
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if(a == 100)
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else if(a == 200)
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{
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{
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printf("a is equal to 100\n");
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printf("a is equal to 200\n");
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}
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}
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else if(a == 200)
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else if(a == 300)
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{
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{
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printf("a is equal to 200\n");
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printf("a is equal to 300\n");
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}
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}
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else if(a == 300)
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else
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{
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{
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printf("a is equal to 300\n");
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printf("a is more than 300\n");
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}
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}
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else
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```
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{
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#### Result
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printf("a is more than 300\n");
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}
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`a is equal to 300`
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```
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## 4. Nested if statement
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#### Result
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It is always legal in C programming to nest if-else statements, which means you can use one if or else if statement inside another if or else if statement(s).
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`a is equal to 300`
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#### Syntax
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```C
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## 4. Nested if statement
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if(boolean_expression_1)
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It is always legal in C programming to nest if-else statements, which means you can use one if or else if statement inside another if or else if statement(s).
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{
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//Executed when boolean_expression_1 is true
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#### Syntax
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if(boolean_expression_2)
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```C
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{
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if(boolean_expression_1)
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//Executed when both boolean_expression_1 and boolean_expression_2 are true
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{
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}
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//Executed when boolean_expression_1 is true
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}
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if(boolean_expression_2)
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{
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```
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//Executed when both boolean_expression_1 and boolean_expression_2 are true
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#### Example
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}
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```C
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}
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int a = 100;
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int b = 200;
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```
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if(a == 100)
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#### Example
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{
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```C
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printf("a is equal to 100\n" );
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int a = 100;
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if(b == 200)
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int b = 200;
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{
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if(a == 100)
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printf("b is equal to 200\n");
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{
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}
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printf("a is equal to 100\n" );
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}
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if(b == 200)
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{
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```
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printf("b is equal to 200\n");
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#### Result
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}
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}
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```bash
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a is equal to 100
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```
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b is equal to 200
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#### Result
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```
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```bash
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## 5. Switch Case Statement
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a is equal to 100
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The switch statement is often faster than nested if...else (not always). Also, the syntax of switch statement is cleaner and easy to understand.
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b is equal to 200
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```
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### Syntax of switch case
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```
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## 5. Switch Case Statement
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switch (n)
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The switch statement is often faster than nested if...else (not always). Also, the syntax of switch statement is cleaner and easy to understand.
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{
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case constant1:
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### Syntax of switch case
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// code to be executed if n is equal to constant1;
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```
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break;
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switch (n)
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{
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case constant2:
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case constant1:
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// code to be executed if n is equal to constant2;
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// code to be executed if n is equal to constant1;
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break;
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break;
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.
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.
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case constant2:
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.
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// code to be executed if n is equal to constant2;
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default:
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break;
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// code to be executed if n doesn't match any constant
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.
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}
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.
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```
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.
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When a case constant is found that matches the switch expression, control of the program passes to the block of code associated with that case.
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default:
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// code to be executed if n doesn't match any constant
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In the above pseudocode, suppose the value of n is equal to constant2. The compiler will execute the block of code associate with the case statement until the end of switch block, or until the break statement is encountered.
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}
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```
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The break statement is used to prevent the code running into the next case.
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When a case constant is found that matches the switch expression, control of the program passes to the block of code associated with that case.
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### Example:
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```C
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In the above pseudocode, suppose the value of n is equal to constant2. The compiler will execute the block of code associate with the case statement until the end of switch block, or until the break statement is encountered.
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// Program to create a simple calculator
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// Performs addition, subtraction, multiplication or division depending the input from user
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The break statement is used to prevent the code running into the next case.
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# include <stdio.h>
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### Example:
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```
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int main()
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// Program to create a simple calculator
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{
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// Performs addition, subtraction, multiplication or division depending the input from user
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char operator;
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# include <stdio.h>
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double firstNumber,secondNumber;
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int main()
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printf("Enter an operator (+, -, *, /): ");
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{
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scanf("%c", &operator);
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char operator;
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printf("Enter two operands: ");
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double firstNumber,secondNumber;
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scanf("%lf %lf",&firstNumber, &secondNumber);
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printf("Enter an operator (+, -, *, /): ");
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switch(operator)
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scanf("%c", &operator);
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{
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case '+':
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printf("Enter two operands: ");
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printf("%.1lf + %.1lf = %.1lf",firstNumber, secondNumber, firstNumber+secondNumber);
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scanf("%lf %lf",&firstNumber, &secondNumber);
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break;
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switch(operator)
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case '-':
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{
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printf("%.1lf - %.1lf = %.1lf",firstNumber, secondNumber, firstNumber-secondNumber);
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case '+':
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break;
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printf("%.1lf + %.1lf = %.1lf",firstNumber, secondNumber, firstNumber+secondNumber);
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break;
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case '*':
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printf("%.1lf * %.1lf = %.1lf",firstNumber, secondNumber, firstNumber*secondNumber);
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case '-':
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break;
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printf("%.1lf - %.1lf = %.1lf",firstNumber, secondNumber, firstNumber-secondNumber);
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break;
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case '/':
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if(secondNumber==0){
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case '*':
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printf("division with zero is not allowed\n");
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printf("%.1lf * %.1lf = %.1lf",firstNumber, secondNumber, firstNumber*secondNumber);
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break;
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break;
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//Avoid runtime error of division with zero
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}
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case '/':
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printf("%.1lf / %.1lf = %.1lf",firstNumber, secondNumber, firstNumber/secondNumber);
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printf("%.1lf / %.1lf = %.1lf",firstNumber, secondNumber, firstNumber/secondNumber);
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break;
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break;
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// operator is doesn't match any case constant (+, -, *, /)
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// operator is doesn't match any case constant (+, -, *, /)
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default:
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default:
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printf("Error! operator is not correct");
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printf("Error! operator is not correct");
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}
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}
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return 0;
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return 0;
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}
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}
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```
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```
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### Output
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```
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### Output
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Enter an operator (+, -, *,): -
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```
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Enter two operands: 32.5
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Enter an operator (+, -, *,): -
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12.4
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Enter two operands: 32.5
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32.5 - 12.4 = 20.1
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12.4
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```
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32.5 - 12.4 = 20.1
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The '-' operator entered by the user is stored in operator variable. And, two operands 32.5 and 12.4 are stored in variables firstNumber and secondNumber respectively.
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```
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The '-' operator entered by the user is stored in operator variable. And, two operands 32.5 and 12.4 are stored in variables firstNumber and secondNumber respectively.
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Then, control of the program jumps to
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```
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Then, control of the program jumps to
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printf("%.1lf / %.1lf = %.1lf",firstNumber, secondNumber, firstNumber/firstNumber);
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```
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```
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printf("%.1lf / %.1lf = %.1lf",firstNumber, secondNumber, firstNumber/firstNumber);
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Finally, the break statement ends the switch statement.
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```
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Finally, the break statement ends the switch statement.
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If break statement is not used, all cases after the correct case is executed.
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If break statement is not used, all cases after the correct case is executed.
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## finding the Bigger among two numbers using if else statement.
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```C
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## 6. Ternary operation
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int a,b;
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The ternary operator (AKA conditional operator) is an operator that takes three arguments. The first argument is a comparison argument, the second is the result upon a true comparison , and the third is the result upon a flase comparison .It can be thought of as a shortened way of writing an if-else statement. It is often used to to assign variables based on the result of a comparison.
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printf("Enter the first number: \n");
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scanf("%d",&a);
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#### Syntax
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printf("Enter the second number: \n");
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```C
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scanf("%d",&b);
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v = (conditional_statement) ? value_if_true : value_if_false
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//comparing the numbers
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```
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if(a>b)
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{
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#### Example
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printf("A is the Bigger number");
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```C
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}
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int a, b = 10, c = 100;
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else
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a = (b > c) ? 1 : 2;
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{
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printf("%d", a);
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printf("B is the bigger number");
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```
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}
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```
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#### Result
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## 6. Ternary operation
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`2`
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The ternary operator (AKA conditional operator) is an operator that takes three arguments. The first argument is a comparison argument, the second is the result upon a true comparison , and the third is the result upon a flase comparison .It can be thought of as a shortened way of writing an if-else statement. It is often used to to assign variables based on the result of a comparison.
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### More Information
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https://www.dotnettricks.com/learn/c/conditional-statements-if-else-switch-ladder
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#### Syntax
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https://www.programiz.com/c-programming/c-if-else-statement
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```C
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http://www.tutorialspoint.com/ansi_c/c_control_statements.htm
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v = (conditional_statement) ? value_if_true : value_if_false
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```
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#### Example
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```C
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int a, b = 10, c = 100;
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a = (b > c) ? 1 : 2;
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printf("%d", a);
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```
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#### Result
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`2`
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Reference in New Issue
Block a user