C Program to Display a String in Capital Letters Only

Introduction

In this article, we will explore two different approaches to create a C program to display a string in capital letters only.

The first approach will utilize library functions, while the second approach will implement the conversion without using any library functions.

By understanding both methods, you can choose the one that best suits your requirements.

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Let’s dive into the details and learn how to implement these programs step by step.

Understanding the Problem

Before we delve into the programs, let’s understand the problem at hand. We need to create C programs that take a string as input and display the string with all its characters converted to capital letters.

For example, if the input string is “Hello, World!”, the programs should display “HELLO, WORLD!” as the output.

The programs should preserve the positions of all non-alphabetic characters, such as punctuation marks or spaces.

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Approach 1: Using Library Functions

The first approach involves utilizing library functions to convert the characters to uppercase.

The C standard library provides the toupper() function, which converts a lowercase character to its uppercase equivalent.

By iterating over each character of the string and applying the toupper() function, we can achieve the desired result.

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Code Implementation

#include <stdio.h>
#include <ctype.h>

void displayInCapitalLetters(char *str) {
    int i = 0;
    char c;
    
    while (str[i] != '\0') {
        c = str[i];
        
        if (isalpha(c)) {
            c = toupper(c);
        }
        
        printf("%c", c);
        i++;
    }
}

int main() {
    char str[] = "Hello, World!";
    
    printf("Original String: %s\n", str);
    printf("Capital Letters Only: ");
    
    displayInCapitalLetters(str);
    
    return 0;
}

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Approach 2: Without Using Library Functions

The second approach involves manually converting the characters to uppercase without relying on library functions.

This approach requires a bit more coding, but it avoids using external functions, which can be beneficial in certain scenarios where library functions are restricted.

Code Implementation

#include <stdio.h>

void displayInCapitalLetters(char *str) {
    int i = 0;
    char c;
    
    while (str[i] != '\0') {
        c = str[i];
        
        if (c >= 'a' && c <= 'z') {
            c = c - 32;
        }
        
        printf("%c", c);
        i++;
    }
}

int main() {
    char str[] = "Hello, World!";
    
    printf("Original String: %s\n", str);
    printf("Capital Letters Only: ");
    
    displayInCapitalLetters(str);
    
    return 0;
}

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Example Usage

Let’s run the programs with the given input string “Hello, World!” to see the output:

Original String: Hello, World!
Capital Letters Only: HELLO, WORLD!

As we can see, both programs successfully convert the input string to capital letters only, preserving the positions of non-alphabetic characters.

FAQs

Conclusion

In this article, we explored two different approaches to creating C program to display a a string in capital letters only.

The first approach utilized the toupper() function from the C standard library, while the second approach manually converted the characters without using any library functions.

Both programs achieved the desired result, and you can choose the approach based on your specific requirements.

Now you have the knowledge to implement C programs that convert strings to capital letters, giving you greater control over string manipulation.