C language isupper() function: determine whether a character is an uppercase English letter

Function name : isupper

Header file : <ctype.h>

Function prototype : int isupper(int ch);

Function : Determine whether the character is an uppercase English letter

Parameters : int ch character to be checked

Return value : If ch is not an uppercase English letter, return 0; if ch is an uppercase English letter, return non-0

Program example : Determine whether the entered characters are uppercase English letters

 #include<ctype.h>#include<stdio.h>intmain(){charch;printf(inputacharacter:);scanf(%c,&ch);if(isupper(ch)){printf(%cisupper.,ch) ;}else{printf(%cisnotuppper.,ch);}putchar('n');return0;}

Running results

 inputacharacter:GGisupper.