C Recursion
C Recursion
In this tutorial, you will learn to create a recursive function in C programming.
Posted By Manisha Gupta
A function that calls itself is known as a recursive function. And, this technique is known as recursion.
How recursion works?
void recurse()
{
... .. ...
recurse();
... .. ...
}
int main()
{
... .. ...
recurse();
... .. ...
}
The recursion continues until some condition is met to prevent it.
To prevent infinite recursion, if...else statement (or similar approach) can be used where one branch makes the recursive call and other doesn't.
Example: Sum of Natural Numbers Using Recursion
#include <stdio.h>
int sum(int n);
int main()
{
int number, result;
printf("Enter a positive integer: ");
scanf("%d", &number);
result = sum(number);
printf("sum = %d", result);
return 0;
}
int sum(int num)
{
if (num!=0)
return num + sum(num-1); // sum() function calls itself
else
return num;
}
Output
Enter a positive integer:3 sum = 6
Initially, the
sum() is called from the main() function with number passed as an argument.
Suppose, the value of num is 3 initially. During next function call, 2 is passed to the
sum()function. This process continues until num is equal to 0.
When num is equal to 0, the if condition fails and the else part is executed returning the sum of integers to the
main() function.
Advantages and Disadvantages of Recursion
Recursion makes program elegant and more readable. However, if performance is vital then, use loops instead as recursion is usually much slower.
Note that, every recursion can be modeled into a loop.
Recursion Vs Iteration? Need performance, use loops, however, code might look ugly and hard to read sometimes. Need more elegant and readable code, use recursion, however, you are sacrificing some performance.
