❮ C Exercise Example17 C Function Tmpnam ❯

Recursion

Recursion refers to the method of using the function itself within its definition.

For example:

The syntax format is as follows:

void recursion()
{
   statements;
   ... ... ...
   recursion(); /* Function calls itself */
   ... ... ...
}

int main()
{
   recursion();
}

Flowchart:

C language supports recursion, meaning a function can call itself. However, when using recursion, the programmer needs to define an exit condition from the function, otherwise it will enter an infinite loop.

Recursive functions play a crucial role in solving many mathematical problems, such as calculating the factorial of a number, generating Fibonacci series, etc.

Factorial of a Number

The following example uses a recursive function to calculate the factorial of a given number:

Example

#include <stdio.h>

double factorial(unsigned int i)
{
   if(i <= 1)
   {
      return 1;
   }
   return i * factorial(i - 1);
}
int  main()
{
    int i = 15;
    printf("%d 的阶乘为 %f\n", i, factorial(i));
    return 0;
}

When the above code is compiled and executed, it produces the following result:

15 的阶乘为 1307674368000.000000

Fibonacci Series

The following example uses a recursive function to generate the Fibonacci series for a given number:

Example

#include <stdio.h>

int fibonaci(int i)
{
   if(i == 0)
   {
      return 0;
   }
   if(i == 1)
   {
      return 1;
   }
   return fibonaci(i-1) + fibonaci(i-2);
}

int  main()
{
    int i;
    for (i = 0; i < 10; i++)
    {
       printf("%d\t\n", fibonaci(i));
    }
    return 0;
}

When the above code is compiled and executed, it produces the following result:

❮ C Exercise Example17 C Function Tmpnam ❯