Why this program showing error on sololearn coding ground while runs on windows with same compiler version gcc 9.2.0

Question

#include <stdio.h>
#include <string.h>
int main() {
char str[100];
fgets(str,100,stdin);
printf ("%s",strlwr(str));
return 0;
}

Answer 1

`strlwr` and `strupr` are not part of the standard library, it may or may not be implemented in the string.h header file. See the note on the following page:

https://fresh2refresh.com/c-programming/c-strings/c-strlwr-function/

Answer 2

Thanks