Remove Duplicate Characters from a String

Code

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

void remove_duplicates(char *str) {
	//Your logic here
    uint8_t has_appeared[128] = {0};

    int len = 0;
    while (*(str+len) != '\0') ++len;

    for (int i = 0; i < len; ++i) {
        if (!has_appeared[*(str+i)]) {
            has_appeared[*(str+i)] = 1;
        } else {
            for (int j = i; j < len; ++j) {
                *(str+j) = *(str+j+1);
            }
            --len;
            --i;
        }
    }
}

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