Remove Duplicate Characters from a String

Code

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

void remove_duplicates(char *str) {
    int seen[256]={0};
    int j =0;
	for(int i=0; str[i]!='\0'; i++){
        char ch = str[i];

        if(!seen[ch]){
            seen[ch] = 1;
            str[j++] = ch;
        }
    }
    str[j]='\0'; //This important
    }

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;
}


///////////

// void remove_duplicates(char *str) {
//     uint8_t hash[256] = {0};  // 1-byte flags per ASCII char
//     uint8_t read = 0, write = 0;

//     while (str[read] != '\0') {
//         uint8_t ch = (uint8_t)str[read];
//         if (!hash[ch]) {
//             hash[ch] = 1;
//             str[write++] = str[read];
//         }
//         read++;
//     }
//     str[write] = '\0';  // Null terminate final string
// }

Solving Approach