How to debug "initialized element is not a compile-time constant" and "expected identifier" errors

Question

I'm trying to retrieve an input from the user and then apply it to the portion of mario.c that makes prints the pyramid. After several hours of trial and error, here is what I have been able to come up with so far:

#include <stdio.h>
#include <cs50.h>

int main(void);

int (n);
int n = GetInt();

do
{
    n = GetInt();
}
while (n !> 0 && n !< 23)


for (int i = 0; i < n; i++)
{
    printf ("##");
}

When I attempt to compile this program, I get the following errors:

mario.c:7:9: error: initializer element is not a compile-time constant
int n = GetInt();
    ^~~~~~~~
mario.c:9:1: error: expected identifier or '('
do
^
mario.c:13:1: error: expected identifier or '('
while (n !> 0 && n !< 23)
^
3 errors generated.

No matter what I do to my code, I always get these three errors, at the very least.

• What is a 'compile-time constant'?
• To what are the 'expected identifier' errors referring?
• What am I doing wrong and what can I do to start debugging?

Answer 1

You have the right idea behind how the code works, it's just your English to C needs some practice (understandably).

int main(void);

This is, as its name suggests, the "main" method. Essentially, when you say to run the program, it looks for main(void) and goes from there. Therefore, all your other code should be inside this function, Which will take care of error number one.

int main(void)
{
    // code goes here
}

Next up: The do-while. First, after the closing ) in the while there should be a ;. Next, !> and !< aren't recognized by C. Your options are ==, !=, > and <. So instead of saying "while n isn't greater than 0 and isn't less than 23", instead try "while n is outside the boundries (of 0 and 23)".

Let me know if you could use more guidance, particularly on the second part. You're doing well so far!

Answer 2

Your problem now is that you have written ; after int main (void). Delete ; and everything should be right. Your main function should be:

int main(void)
{ 
  int (n); 
  int n = GetInt(); 
  do { 
       n = GetInt(); 
  } while (n < 0 && n > 23); 
  for (int i = 0; i < n; i++) { 
    printf("##") 
  }
}