Example of Functions

In this lesson, we will see several examples of functions. We will go through the following topics:

• Function sum of int
• Function sum of float
• Function min int
• Function average float

Function sum int

In this topic, we will create a function that gives us the sum of two integers.

#include <stdio.h>

/*
    Type of return: int -> because the sum of two integers is an integer
    Name: sum
    Parameters: int a, int b -> the two parts of our sum
    Code: a + b
*/

int sum(int a, int b){
    int s = a + b;
    return s;
}

int main(){
    int x = sum(2, 3); // x receives the value returned by the function sum with the parameters 2 and 3

    printf("%d\n", x);
}
/* Output:
5

*/

In our "sum" function, declared in the above code, we have the return command. This command indicates that the function must return a certain value which, in this case, is the variable. As soon as the return command is executed, the function returns the value and is terminated. Therefore, any code that is after return will not be executed (if the return command has been executed before).

Therefore, our program will start with the main function and will assign the value of "sum(2, 3)" to . The function, when called, will return , which is the sum of and . After that, the function is terminated and the program returns to main. Then the printf command is executed, printing , and our program comes to an end.

Function sum float

In this topic, we will create a function that provides the sum of two floats.

#include <stdio.h>

/*
    Type of return: float -> because the sum of two reals is a real
    Name: sum
    Parameters: float a, float b -> the two parts of our sum
    Code: a + b
*/

float sum(float a, float b){
    float s = a + b;
    return s;
}

int main(){
    float x, y;

    scanf("%f %f", &x, &y);

    printf("%.1f\n", sum(x, y));
}

Our code above defines a "sum" function that receives two real numbers and returns the sum of them, which is also a real number.

In the main function, two real numbers and are read. After that, the printf command will print a value as a float, with only 1 decimal place. This value will be the one returned by the "sum" function, having and as parameters.

Function min int

In this topic, we will create a function that gives us the smallest of two integers.

#include <stdio.h>

/*
    Type of return: int -> because the smallest of two integers is an integer
    Name: min
    Parameters: int a, int b -> the two integers to be analyzed
    Code: an if-else structure
*/

int min(int a, int b){
    if(a < b){ // checks if a is lower than b
        return a;
    }
    else{ // otherwise
        return b;
    }
}

int main(){
    int x, y;

    scanf("%d %d", &x, &y);

    printf("%d\n", min(x, y));
}

Note that in the above code, unlike what has been seen so far, there are two return commands.

When the function is called, it checks if the value of is lower than . If this happens, the value of will be returned and the function will end. Therefore, any remaining code in the function will be ignored.

However, if is not lower than , then the first return will not be executed. Therefore, the function will continue to operate and the second return will be executed, returning the value of .

Note also that if is equal to , then the first return will not be executed, but the second will. This is because the statement is false.

Function average float

In this topic, we will create a function that gives us the average between two real numbers.

#include <stdio.h>

float average(float a, float b){
    return (a+b)/2.0;
}

int main(){
    float x, y;

    scanf("%f %f", &x, &y);

    printf("%.2f\n", average(x, y));
}

As an incentive, try to interpret the operation of the above code yourself. After that, use your creativity to create your own functions, using all the knowledge acquired so far.

During this topic, it is important that you try to solve all the next exercises using functions 😉.

Until the next lesson!