C Operators

Operators in C are symbols that perform actions on values, such as adding numbers, assigning a value, or comparing two expressions. They let you build expressions that calculate results and make decisions.

Arithmetic Operators

Arithmetic operators work with numeric values. You have already used = to store values; arithmetic operators are what let you calculate new ones.

Operator	Meaning	Example
+	Addition	a + b
-	Subtraction	a - b
*	Multiplication	a * b
/	Division	a / b
%	Remainder	a % b

#include <stdio.h>

int main(void)
{
    int a = 17;
    int b = 5;

    printf("Sum: %d\n", a + b);
    printf("Difference: %d\n", a - b);
    printf("Product: %d\n", a * b);
    printf("Integer division: %d\n", a / b);
    printf("Remainder: %d\n", a % b);

    return 0;
}

Output:

Sum: 22
Difference: 12
Product: 85
Integer division: 3
Remainder: 2

Because a and b are both integers, a / b performs integer division. The decimal part is discarded, so 17 / 5 gives 3. The remainder operator % gives what is left over.

Assignment Operators

The assignment operator = stores the value on its right into the variable on its left. C also has shortcut assignment operators that combine a calculation with assignment.

#include <stdio.h>

int main(void)
{
    int score = 10;

    score += 5;
    printf("After bonus: %d\n", score);

    score *= 2;
    printf("After doubling: %d\n", score);

    score -= 4;
    printf("Final score: %d\n", score);

    return 0;
}

Output:

After bonus: 15
After doubling: 30
Final score: 26

The statement score += 5; means the same thing as score = score + 5;. Similar shortcuts include -=, *=, /=, and %=.

Increment and Decrement

The operators ++ and -- add or subtract 1 from a variable. They are common in counters and loops.

#include <stdio.h>

int main(void)
{
    int count = 3;

    count++;
    printf("After increment: %d\n", count);

    count--;
    printf("After decrement: %d\n", count);

    return 0;
}

Output:

After increment: 4
After decrement: 3

Comparison Operators

Comparison operators test relationships between values. In C, a true comparison produces 1, and a false comparison produces 0.

Operator	Meaning
==	Equal to
!=	Not equal to
>	Greater than
<	Less than
>=	Greater than or equal to
<=	Less than or equal to

#include <stdio.h>

int main(void)
{
    int age = 20;
    int minimum_age = 18;

    printf("Old enough: %d\n", age >= minimum_age);
    printf("Exactly 18: %d\n", age == minimum_age);

    return 0;
}

Output:

Old enough: 1
Exactly 18: 0

Be careful not to confuse = and ==. Use = to assign a value, and use == to compare two values.

Logical Operators

Logical operators combine or reverse comparisons. They are especially useful in conditions.

Operator	Meaning
&&	AND: true when both sides are true
||	OR: true when at least one side is true
!	NOT: reverses true and false

#include <stdio.h>

int main(void)
{
    int age = 20;
    int has_ticket = 1;

    printf("Can enter: %d\n", age >= 18 && has_ticket == 1);
    printf("Needs help: %d\n", !(age >= 18));

    return 0;
}

Output:

Can enter: 1
Needs help: 0

Operator Precedence

C follows precedence rules to decide which operators run first. Multiplication and division happen before addition and subtraction, so 2 + 3 * 4 is 14, not 20.

Use parentheses when they make an expression clearer or when you need a different order.

#include <stdio.h>

int main(void)
{
    int first = 2 + 3 * 4;
    int second = (2 + 3) * 4;

    printf("Without parentheses: %d\n", first);
    printf("With parentheses: %d\n", second);

    return 0;
}

Output:

Without parentheses: 14
With parentheses: 20

The key idea is that operators turn values into expressions: they calculate, assign, compare, and combine results. Next, you will use these expressions more often when writing conditions and control flow.