I am just getting introduced to string in C, and my teacher uses CodeBlocks on windows and I'm using Xcode. He introduced me to this:

#include <stdio.h>
#include <string.h>
int main()
{
    char name[15];
    printf("Enter your name ");
    scanf("%[^\n]s\n",&name);
    printf("Welcome, %s !",name);
    size_t a=strlen(name);
    printf("Your name is %zu\n",a);
    strupr(name);
    printf("\n")
}

But when I do this same program in Xcode, strupr(name); doesn't work and shows the error:

Implicit declaration of function 'strupr' is invalid in C99.

So I came back to SO to look for possible solutions. There was one where it said to go to language dialect and change it to C11. I did it, but it still would not execute, showing the same error message. Do I need to do something else to make it run?

Thanks