C Program to Remove Duplicate Characters from a String

🧹 C Program to Remove Duplicate Characters from a String

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

int main() {
    int i, j, k;
    char str[100];

    printf("Enter the string:\n");
    scanf(" %[^\n]", str);  // space before %[^\n] to handle newline

    for (i = 0; str[i] != '\0'; i++) {
        j = i + 1;
        while (str[j] != '\0') {
            if (str[j] == str[i]) {
                // Shift all characters one position to the left
                for (k = j; str[k] != '\0'; k++) {
                    str[k] = str[k + 1];
                }
                // Don't increment j here — next character is already shifted
            } else {
                j++;
            }
        }
    }

    printf("After removing Duplicate Elements in Given String: %s\n", str);
    return 0;
}
  

📝 Explanation:

This program reads a string from the user and removes duplicate characters by shifting the remaining characters left whenever a duplicate is found.

💡 Sample Output:

Enter the string:
programming
After removing Duplicate Elements in Given String: progamin
  

🔍 Keywords:

remove duplicates from string in C, string manipulation in C, C string interview programs, delete repeated characters, remove duplicate characters in C