Parameters

Learn to pass parameters to a function and call by value.

Taking data with parameters

Parameters specify the data a function takes from outside. Each parameter has a type and a name.

void greet(char name[]) {
    printf("Hello, %s!\n", name);
}

int main(void) {
    greet("Anna");  /* Hello, Anna! */
}

When calling, you put a value (argument) inside the parentheses. Parameter and argument are different: the parameter is in the definition, the argument is in the call.

Multiple parameters

Multiple parameters are separated by commas. Each parameter needs its own type.

int divide(int dividend, int divisor) {
    return dividend / divisor;
}

int seven = divide(14, 2);  /* seven = 7 */

Order matters: the first argument goes to the first parameter, the second to the second. divide(2, 14) gives a different result (0).

Exercise Sum of three numbers

Define int add(int a, int b, int c) with body return a + b + c;. Call printf("%d\n", add(2, 3, 4)); from main. Output should be 9.

Show example solution

#include <stdio.h>

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

int main(void) {
    printf("%d\n", add(2, 3, 4));
    return 0;
}

Test yourself

Match parameter concepts

parameter

in definition
argument

in call
type

int, char, double
name

identifier

Two-parameter definition

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

Show answer

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

What is written for each parameter in a parameter list?
- Value
- Only name
- Only type
- Type and name
Show answer

Type and name — Each parameter has a type and a name together.

Next lesson: Function prototypes

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies