C program uses recursion to find the sum of natural numbers

Comprehensive Collection of C Programming Examples

In this example, you will learn to use recursive functions to find the sum of natural numbers.

To understand this example, you should understand the followingC programming languageTopic：

• C user-defined function

• C recursion

Positive number1,2,3 ...is called natural numbers. The following program retrieves a positive integer from the user and then calculates the sum of the given number.

Access this page to　 Natural number sum using loop.

Natural number sum using recursion

#include　<stdio.h>
int　addNumbers(int　n);
int　main()　{
　　　　int　num;
　　　　printf("Enter a positive integer:　");
　　　　scanf("%d",　&num);
　　　　printf("Sum　=　%d",　addNumbers(num));
　　　　return　0;
}
int　addNumbers(int　n)　{
　　　　if　(n　!=　0)
　　　　　　　　return　n　+　addNumbers(n　-　1);
　　　　else
　　　　　　　　return　n;
}

Output result

Enter a positive integer:　20
Sum　=　210

Assuming the user entered20.

Initially, call addNumbers() from main(), and pass in20 as a parameter.

number20 is added to addNumbers(19) result.

to be passed in the next function call from addNumbers() to addNumbers().19, which will be added to the addNumbers(18result. This process continues until n equals 0.

No recursive calls are made when n equals 0. This ultimately returns the integer and passes it back to the main() function.

Comprehensive Collection of C Programming Examples