Remove Duplicate Characters from a String

Code

#include <stdio.h>
#include <stdint.h>

void remove_duplicates(char *str) {
	//Your logic here
        int index = 0;                  // Index for the new string
    int seen[256] = {0};            // To track ASCII characters (0–255)

    for (int i = 0; str[i] != '\0'; i++) {
        if (!seen[(unsigned char)str[i]]) {   // If char not seen before
            seen[(unsigned char)str[i]] = 1;  // Mark it as seen
            str[index++] = str[i];            // Keep the character
        }
    }
    str[index] = '\0'; // End the new string
}
   

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);

    // Remove newline
    uint8_t i = 0;
    while (str[i]) {
        if (str[i] == '\n') {
            str[i] = '\0';
            break;
        }
        i++;
    }

    remove_duplicates(str);
    printf("%s", str);
    return 0;
}

Solving Approach