Add and subtract

Add and test the addition and subtraction functions.

The add and subtract functions

The first functions of the calculator are add and subtract. Both take two ints and return an int:

int add(int a, int b) {
    return a + b;
}

int subtract(int a, int b) {
    return a - b;
}

We call these from main as add(5, 3); the result is 8. subtract(5, 3) gives 2.

Exercise Add add and subtract

Add int add(int a, int b) and int subtract(int a, int b) functions to the skeleton below. Call both in main: printf("%d\n", add(5, 3)); and printf("%d", subtract(5, 3));. Keep the existing printf.

Show example solution

#include <stdio.h>

int add(int a, int b) {
    return a + b;
}

int subtract(int a, int b) {
    return a - b;
}

int main(void) {
    printf("Calculator\n");
    printf("%d\n", add(5, 3));
    printf("%d", subtract(5, 3));
    return 0;
}

Calling functions from main

After defining functions, you can call them from main. A call is the function name followed by arguments in parentheses:

int result = add(5, 3);
printf("%d", result);

Or use them directly inside printf: printf("%d", add(5, 3));. This is shorter and needs no intermediate variable.

Test yourself

What does add(5, 3) return?
```
int add(int a, int b) {
    return a + b;
}
```
- 8
- 53
- 2
- 15
Show answer

8 — The add function returns a + b.

Complete the return statement

int add(int a, int b) { return a ____ b; }

Show answer

int add(int a, int b) { return a + b; }

Match the operators

+

Addition
-

Subtraction
*

Multiplication
/

Division

Next lesson: Multiply and divide

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