Remove Duplicate Characters from a String

Code

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

void remove_duplicates(char *str) 
{
	int i;
    int j=0;
    int seen[256] = {0}; 
    for(i=0;str[i]!='\0';i++)
    {
         unsigned char ch=str[i];  
         if (!seen[ch])   // if character not seen before
        {
            seen[ch] = 1;   // mark as seen
            str[j++] = ch;  // keep the character
        }
    }
    str[j]='\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