Replace a Character in a Given String Using C Programming

Introduction

In this post, you will learn how to replace a character in a given string using a C program. Replacing characters is a common task in string manipulation, and understanding this process is essential for beginner programmers working with character arrays in C.

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C Program to Replace a Character in a Given String

#include <stdio.h>

int main() {
    char str[100], oldChar, newChar;
    int i;

    printf("Enter a string: ");
    fgets(str, sizeof(str), stdin);

    printf("Enter the character to replace: ");
    scanf("%c", &oldChar);
    getchar();  // consume newline character

    printf("Enter the new character: ");
    scanf("%c", &newChar);

    for (i = 0; str[i] != '\0'; i++) {
        if (str[i] == oldChar) {
            str[i] = newChar;
        }
    }

    printf("Updated string: %s", str);

    return 0;
}

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Explanation

• fgets() reads the entire input string including spaces.
• The user provides the character to be replaced and the new character.
• The loop iterates through each character in the string and replaces it if it matches.
• The final updated string is displayed.

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Sample Output

Enter a string: hello world
Enter the character to replace: l
Enter the new character: x
Updated string: hexxo worxd

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Use Cases

• Replacing sensitive or special characters.
• Creating text formatters or filters.
• Enhancing understanding of string traversal in C.