Remove Duplicate Characters from a String

Code

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

void remove_duplicates(char *str) {
	unsigned char seenAlpha[256] = {0};

    int read = 0;
    int write = 0;
    while(str[read] != '\0'){

        unsigned char index = (unsigned char)str[read];

        if(!seenAlpha[index]){
            seenAlpha[index] = 1;
            str[write] = str[read];
            write++;
        }
        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