Remove Duplicate Characters from a String

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

void remove_duplicates(char *str) {
    for(int i = 0; str[i] != '\0';i++)
    {
        if(str[i] != -1)
        {
        for(int j = i+1; str[j] != '\0'; j++)
        {
            if(str[i] == str[j])
            {
                str[j] = -1;
            }
        }
        printf("%c",str[i]);
        }
    }
	//Your logic here
    }

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;
}