Remove Duplicate Characters from a String

Code

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

void remove_duplicates(char *str) {
    uint8_t seen[256] = {0};
    int read = 0, write = 0;

    while (str[read] != '\0') {
        unsigned char ch = (unsigned char)str[read];
        if (!seen[ch]) {
            seen[ch] = 1;           // mark as seen
            str[write++] = str[read];  // keep this char
        }
        // else skip duplicate
        read++;
    }
    str[write] = '\0';
}

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