/* Puzzle S01 -- detect upper case characters */
#include <stdio.h>
#include <stdlib.h>
int isUppercase( int ch )
{
return ch>='A' && ch<='Z' ;
}
int main()
{
int trials[] = {'a', 'B', 'Z', ' ', '+', 'z', 'Z', 0x33 };
int j, ch;
for ( j=0; j<sizeof(trials)/sizeof(int); j++ )
{
ch = trials[j];
if ( isUppercase( ch ) )
printf("%c is upper case\n", ch);
else
printf("%c is NOT upper case\n", ch);
}
return 0;
}
Comments:
(1) The literal 'a' designates an int with the
ASCII code for 'a' in the low order byte and zeros in three other bytes.
(2) The array trials[] is an
array of int, so sizeof(trials)/sizeof(int) gives
the number of cells.
(3) C envirnoments have
several "is" functions described in
<ctype.h>
| Function | Description |
|---|---|
| int isalnum(int ch) | is ch alphanumeric? |
| int isalpha(int ch) | is ch alphabetic? |
| int isascii(int ch) | is ch in the range 0x00 to 0x7F ? |
| int iscntrl(int ch) | is ch a control character? |
| int isdigit(int ch) | is ch a digit? |
| int islower(int ch) | is ch lower case? |
| int isodigit(int ch) | Can ch be part of an octal constant? |
| int isprint(int ch) | is ch a printable character? |
| int isspace(int ch) | is ch a whitespace character? |
| int ispunct(int ch) | is ch punctuation? |
| int isupper(int ch) | is ch an uppercase character? |
| int iswhite(int ch) | is ch a whitespace character? (same as isspace) |
| int isxdigit(int ch) | Can ch be part of a hexadecimal constant? |
As might be expected, there are minor variations in these functions between different C environments, so you should check your documentation for exact specifications.
To increase portability of your programs, use the functions provided by the C environment rather than write your own.