5. Character classification and conversion library functions

• 
  #include <iostream>
  #include <cctype>
  
  // isalpha(c) non-zero if c is alphabetic, 0 if not 
  // isupper(c) non-zero if c is upper case, 0 if not 
  // islower(c) non-zero if c is lower case, 0 if not 
  // isdigit(c) non-zero if c is digit, 0 if not 
  // isalnum(c) non-zero if isalpha(c) or isdigit(c), 0 if not 
  // isspace(c) non-zero if c is blank, tab, newline, return, formfeed, vertical tab 
  // toupper(c) return c converted to UPPER CASE 
  // tolower(c) return c converted to lower case
  
  int main( )
  {
      char ch = 'A';
      int result = isalpha( ch );
      std::cout << "The result is " << result << '\n';
      return 0;
  }