Remove Duplicate Characters from a String

Code

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

void remove_duplicates(char *str) {
	//Your logic here
    int len;
    for(len=0;str[len]!='\0';len++);

    char buff[len];


    // making it zero for the first occurenece
    int i;
    for(i=0;i<len;i++){
        for(int j=i+1;j<len;j++){
            if(str[i] == str[j]){
                str[j] = 0;
            }
        }
    }

    //allocating in the string 
    int k=0;
    for(i=0;i<len;i++){
        if(str[i] != 0){
         buff[k] = str[i];
         k++;
        }
    }
    buff[k] = '\0';

    //printf("%s",buff);

    for(i=0;i<=k;i++){
        str[i] = buff[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