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Boolean Expressions

A Boolean expression can be evaluated as true or false

The variables x, y, and z have the values shown below:

x=0;
y=5; 
z=8;

Each expression below is TRUE:

Expression	Explanation
x < y	0 is less than 5
z > y	8 is greater than 5
y < z	5 is less than 8
y <= z	5 is less than or equal to 8
x != z	0 is not equal to 8
z >= y	8 is greater than or equal to 5

In C and C++, 0 (zero) is considered false; everything else is true. Therefore, a variable all by itself is also a Boolean expression. For the variables shown above x is false, y is true, and z is true.

Continuing with the same values for x, y, and z, each expression below is FALSE:

Expression	Explanation
x > y	0 is NOT greater than 5
z < y	8 is NOT less than 5
y == z	5 is NOT equal to 8
y <= z	5 is less than or equal to 8
y != y	8 is not equal to 8 is false
x != x	0 is not equal to 0 is also false

NEXT: Drill on Boolean expressions