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

Here, we are going to learn how to find the first capital letter in a string using recursion in C programming language?
Submitted by Nidhi, on July 18, 2021

Problem statement

Read a string from the user and find the first capital letter in a string using recursion.

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

The source code to find the first capital letter in a string using recursion is given below. The given program is compiled and executed using GCC compile on UBUNTU 18.04 OS successfully.

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

#include <stdio.h>
#include <string.h>

char checkCap(char* str)
{
    static int i = 0;
    if (i < strlen(str)) {
        if (str[i] >= 'A' && str[i] <= 'Z') {
            return str[i];
        }
        else {
            i = i + 1;
            return checkCap(str);
        }
    }
    else
        return 0;
}

int main()
{
    char str[64];
    char cap;

    printf("Enter string: ");
    scanf("%[^\n]s", str);

    cap = checkCap(str);

    if (cap == 0)
        printf("Capital letter is not found in the string\n");
    else
        printf("First Capital letter is: %c\n", cap);

    return 0;
}

Output

RUN 1:
Enter string: Hello world, How are you?
First Capital letter is: H

RUN 2:
Enter string: hi, my name is Alex!
First Capital letter is: A

RUN 3:
Enter string: www.includehelp.com
Capital letter is not found in the string

Explanation

In the above program, we created two functions checkCap() and main(). The checkCap() is a recursive function, which is used to find the first capital letter in the string.

In the main() Function, we read the value of string str from the user. Then we called the checkCap() function to found the first capital letter in the string and printed the result on the console screen.

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