Remove Duplicate Characters from a String

Code

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

void remove_duplicates(char *str) {
    int len = 0;
    while(str[len]){
        len++;
    }

    int k= 0;

    for(int i=0;i<len;i++){
        int flag = 0;
        for(int j=0;j<i;j++){
            if(str[i]==str[j]){
                flag =1;
                break;
            }
        }

        if(!flag){
            str[k++] = str[i];
        }
    }
    str[k] = '\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