2018-10-04 14:47:55 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
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								title: C++ If Statement
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
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								# The IF statement.
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								**What does an if statement do?**
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								*  The `if`  statement evaluates the test expression present inside the parenthesis. 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								*  The `if`  statement uses relational and logical operators to make logical expressions. 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  -----------------------------------------------
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  The general form of `if`  statement:
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```cpp
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  if (Test Expression / Condition)
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    // Block of statements if test expression is True
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
									
										
										
										
											2018-10-14 02:22:37 +05:30 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								If there is only one statement after the if statement the '{ }' are not necessarily required . But if there are more number of statements after if statement, then it is mandatory to put all those statements in '{}'.
							 
						 
					
						
							
								
									
										
										
										
											2018-10-04 14:47:55 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								If the value of the test expression is **true** , then the block of
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								code inside the if statement is executed.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								If the value of the test expression is **false** , then the block of
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								code inside the if statement is skipped and your code continues.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								Example `if`  statement:
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```cpp
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  int a = 10;
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  // true statement
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  if (a <  20 ) 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    // execute this block of code
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  // false statement
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  if (a <  0 ) 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    // Skip this block of code.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								Example In C++ :
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```cpp
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  // Program to check if number entered by the user is positive
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  // If negative, the block of code is skipped
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  #include  < iostream > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  using namespace std;
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  int main()
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    int no ;
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    cout < <  "Enter a number: ";
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    cin >> no;
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    // if statement to check if the number is positive
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    if ( no > 0)
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      cout < <  "You have entered a positive number: " < <  no  < <  endl ; 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    // If number is not positive, then if statement is skipped a program continues
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    cout < <  "This step is always printed" < <  endl ; 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    return 0;
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								**Output:**
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								OUTPUT 1:
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								Enter a number: 5
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								You have entered a positive number: 5
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								This step is always printed 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								 ```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								This is the output when the number entered is positive.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								OUTPUT 2:
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								Enter a number:  -1
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								This step is always printed
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								This is the output when the number entered is negative.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< a  href = 'https://repl.it/Mg9X'  target = '_blank'  rel = 'nofollow' > Try the code yourself ! :) < / a >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								_CONGRATULATIONS . This is the end of the article on the IF statement_ 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								 **Good Luck to all of you**  
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								 **Happy Coding ! :)** 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								 **Feel free to ask any queries on FreeCodeCamp's GitHub page or [FreeCodeCamp's Forum .](https://forum.freecodecamp.org/)**