Write a C Program to find First Capital Letter in String using Recursion

Recursion : :

• Recursion is the process of repeating items in a self-similar way. In programming languages, if a program allows you to call a function inside the same function, then it is called a recursive call of the function.

• The C programming language supports recursion, i.e., a function to call itself. But while using recursion, programmers need to be careful to define an exit condition from the function, otherwise it will go into an infinite loop.

• Recursive functions are very useful to solve many mathematical problems, such as calculating the factorial of a number, generating Fibonacci series, etc.

Problem : :

The following C program, using recursion, finds the first capital letter that exists in a string. We have included ctype.h  in order to make use of “isupper(char);” function that’s defined inside the ctype.h headerfile.

The isupper() function returns 1 if the passed character is an uppercase and returns 0 is the passed character is a lowercase.

Here is the source code of the C program to find the first capital letter in a string using recursion. The C program is successfully compiled and run on a Windows system. The program output is also shown below.

SOURCE CODE : :

/* C program to find the first capital letter in a string using recursion */


#include <stdio.h>
#include <string.h>
#include <ctype.h>
 
char caps_check(char *);
 
int main()
{
    char string[20], letter;
 
    printf("Enter a string to find it's first capital letter: ");
    scanf("%s", string);
    letter = caps_check(string);
    if (letter == 0)
    {
        printf("No capital letter is present in %s.\n", string);
    }
    else
    {
        printf("The first capital letter in %s is %c.\n", string, letter);    }
        return 0;
    }
    char caps_check(char *string)
    {
        static int i = 0;
        if (i < strlen(string))
        {
            if (isupper(string[i]))
            {
                return string[i];
            }
            else
            {
                i = i + 1;
                return caps_check(string);
            }
        }
        else return 0;
    }

Output :

************OUTPUT*********************

Enter a string to find it's first capital letter: codezClub

The first capital letter in codezClub is C.