Assignment operators

Learn shortcut assignments with =, +=, -=, *=, /= and ++/--.

Assignment and compound assignment

The = operator assigns the right value to the left variable. +=, -=, *=, /= are compound assignment: they do the operation and the assignment together.

int x = 10;
x += 5;  /* x = x + 5 → 15 */
x -= 3;  /* x = x - 3 → 12 */

Compound assignment reduces repetition and keeps code short. x += 5 means the same as x = x + 5.

Increment and decrement

++ raises a variable by one, -- lowers it by one. They have two forms: post-increment x++ and pre-increment ++x.

int x = 5;
int y = x++;  /* y = 5, x = 6 */
int z = ++x;  /* z = 7, x = 7 */

x++ returns the old value then increments; ++x increments first then returns the new value. Used alone, both behave the same.

Exercise Compound assignment and increment

Define int x = 10;. Add 5 with x += 5;. Subtract 3 with x -= 3;. Increment by one with x++;. Then print x with printf("%d\n", x);. Output should be 13.

Show example solution

#include <stdio.h>

int main(void) {
    int x = 10;
    x += 5;
    x -= 3;
    x++;
    printf("%d\n", x);
    return 0;
}

Test yourself

Compound assignment operator

int x = 10;
x____= 5;  /* x is now 15 */

Show answer

int x = 10;
x+= 5;  /* x is now 15 */

What is the difference between x++ and ++x?
- No difference
- x++ increments first
- x++ returns the value first
- Both are compile errors
Show answer

x++ returns the value first — x++ returns the value first then increments (post-increment).
Match assignment operators

=

direct assignment
+=

add and assign
-=

subtract and assign
++

increment by one

Next lesson: Comparison operators

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies