101 lines
2.2 KiB
Markdown
101 lines
2.2 KiB
Markdown
---
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title: If
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---
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# If
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The if statement executes different blocks of code based on conditions.
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```
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if (condition) {
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// Do something when `condition` is true
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}
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else {
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// Do something when original if `condition` is false
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}
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```
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When `condition` is true, code inside the `if` section executes, otherwise `else` executes. Sometimes you would need to add a second condition. For readability, you should use a `else if` rather than nesting `if` statements.
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```
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if (condition) {
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// Do something if `condition` is true
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}
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else if (anotherCondition) {
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// Do something if `anotherCondition` is true
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}
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else {
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// Do something if `condition` AND `anotherCondition` is false
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}
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```
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Note: `else` and `else if` sections are not required, while `if` is mandatory. Furthermore, `else` and `else if` can only be used following an `if` statement. In the instance when one `if` statement is executed, the following `else if` and `else` statements are ignored.
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## Example
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```
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#include <stdio.h>
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int main () {
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// Local variable definition
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int a = 100;
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// Check the boolean condition
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if(a < 5) {
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// If condition is true then print the following
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printf("a is less than 5!\n" );
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}
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else {
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// If condition is false then print the following
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printf("a is not less than 5!\n" );
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}
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printf("Value of a is : %d\n", a);
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return 0;
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}
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```
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## Output
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```
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-> a is not less than 5!
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-> Value of a is : 10
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```
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## Nested IF Statement
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```
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if( boolean_expression 1) {
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/* Executes when the boolean expression 1 is true */
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if(boolean_expression 2) {
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/* Executes when the boolean expression 2 is true */
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}
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}
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```
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### Example
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```
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#include <stdio.h>
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int main () {
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/* local variable definition */
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int a = 100;
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int b = 200;
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/* check the boolean condition */
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if( a == 100 ) {
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/* if condition is true then check the following */
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if( b == 200 ) {
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/* if condition is true then print the following */
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printf("Value of a is 100 and b is 200\n" );
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}
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}
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printf("Exact value of a is : %d\n", a );
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printf("Exact value of b is : %d\n", b );
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return 0;
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}
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```
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for more info visit <https://www.tutorialspoint.com/cprogramming/nested_if_statements_in_c.htm>
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