Check out example codes for "isalpha c". It will help you in understanding the concepts better.

Code Example 1

#include <stdio.h>
#include <ctype.h> //this is isalpha's library

int main(void)
{
  string variable0 = "a";
  if (isalpha(variable1))
  {
    printf("this will print");
  }
  
  string variable1 = 1;
  if (isalpha(variable1))
  {
    printf("this will NOT print");
  }
}

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