The if statement checks for a condition and executes the proceeding statement or set of statements if the condition is 'true'.
- If there is only one statement inside if, the brackets can be omitted.
- If there are two or more statements, the brackets MUST be used. If not, only the first statement is belong to if.
- condition: a boolean expression (i.e., can be true or false).
The below code will print the even numbers only
The result on Serial Monitor:
※ NOTES AND WARNINGS:
The statements being evaluated inside the parentheses require the use of one or more operators shown below.
Beware of accidentally using the single equal sign (e.g. if (x = 10) ). The single equal sign is the assignment operator, and sets x to 10 (puts the value 10 into the variable x). Instead use the double equal sign (e.g. if (x == 10) ), which is the comparison operator, and tests whether x is equal to 10 or not. The latter statement is only true if x equals 10, but the former statement will always be true.
This is because C++ evaluates the statement if (x=10) as follows: 10 is assigned to x (remember that the single equal sign is the (assignment operator)), so x now contains 10. Then the 'if' conditional evaluates 10, which always evaluates to TRUE, since any non-zero number evaluates to TRUE. Consequently, if (x = 10) will always evaluate to TRUE, which is not the desired result when using an 'if' statement. Additionally, the variable x will be set to 10, which is also not a desired action.