Untitled

Replace a character in a char[] from a function
int main (void)
{
  char* string = "Hello World!";

  printf ("%sn", string);
  replace_char(string, 10, 'a');
  printf ("%sn", string);
}

void replace_char(char str[], int n, char c)
{
  str[n] = c;
}

void replace_char(char*& str, int n, char c)
{
  str = strdup(str);
  str[n] = c;
}

int main()
{
    char* string = "Hello World!";
    string = replace_char(string, 10, 'a');

    // ...
    free(string);
}

const char* conststr = "Hello World!";
char * string = strdup(conststr);

gcc -Wall test.c

char string[] = "Hello World!";