Remove Duplicate Characters from a String

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

void remove_duplicates(char *str) {
	//Your logic here0
    int visited[256] = {0};   // ASCII characters
    int i, j = 0;

    if (str == 0)
        return;

    for (i = 0; str[i] != '\0'; i++)
    {
        unsigned char ch = (unsigned char)str[i];

        if (visited[ch] == 0)
        {
            visited[ch] = 1;
            str[j++] = str[i];   // keep first occurrence
        }
    }

    str[j] = '\0';   // terminate modified string
    }

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;
}