Lesson 3.10. Comparison operators

Lesson 3.9 Summary Lesson 3.11

In C, there are operators for comparing two entities: Is a smaller than b? These operators are mostly used in the conditional structures we will see later:

if (a>b)
  ...
else 
  ...

Comparison operators

There are 6 comparison operators in C:

Operator	name	Example	Type
`==`	is equal to	`a == b`	binary
`!=`	is not equal to	`a != b`	binary
`>`	greater than	`a > b`	binary
`<`	less than	`a < b`	binary
`>=`	greater than or equal to	`a >= b`	binary
`<=`	less than or equal to	`a <= b`	binary

These operators can only return two values:

0 if the test is false ;
1 if the test is true.

Note: the result is always of type int, whatever the type of the operands.

Do not confuse the assignment operator = and the comparison operator ==.

Do not reverse the characters:
>= and != are operators,

=> et =! are not operators.

Quiz

What is the value of the variable x after this instruction?

x = 12 > 8;

true

false

Check

What should be the type of the variable x?

x = 12.5 <= 11.5;

bool

char

int

float

Check Bravo! The type returned by the comparison operators is always int

What is the greater than or equal to operator?

Check

What is the operator to test if two variables are equal?

a = b

a == b

a === b

a eq b

Check Bravo! Do not confuse the assignment operator = with the comparison operator ==.

What does the following program display?

a = 12;
printf ("%d", a == 16);

false

true

Check

What does the following program display?

a = 12;
printf ("%d", a != 16);

false

true

Check Bravo! This time, the test is true, it displays 1.

What does the following program display?

printf ("%d", (5 > a) <= 3 );

It won't compile.

It depends on the variable a.

Check Bravo! The comparison (5 > a) can only return 0 or 1, which will always be less than 3.

Lesson 3.9 Summary Lesson 3.11

Lesson 3.10. Comparison operators

Comparison operators

Quiz

See also