C Tutorial/Data Type/char function

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Using functions isdigit, isalpha, isalnum, and isxdigit

#include <stdio.h>
#include <ctype.h>
 
int main()
{ 
   printf( "%s\n%s%s\n%s%s\n\n", "According to isdigit: ",
       isdigit( "8" ) ? "8 is a " : "8 is not a ", "digit",
       isdigit( "#" ) ? "# is a " : "# is not a ", "digit" );
   printf( "%s\n%s%s\n%s%s\n%s%s\n%s%s\n\n", 
       "According to isalpha:",
       isalpha( "A" ) ? "A is a " : "A is not a ", "letter",
       isalpha( "b" ) ? "b is a " : "b is not a ", "letter",
       isalpha( "&" ) ? "& is a " : "& is not a ", "letter",
       isalpha( "4" ) ? "4 is a " : "4 is not a ", "letter" );
   printf( "%s\n%s%s\n%s%s\n%s%s\n\n", 
       "According to isalnum:",
       isalnum( "A" ) ? "A is a " : "A is not a ", 
       "digit or a letter",
       isalnum( "8" ) ? "8 is a " : "8 is not a ", 
       "digit or a letter",
       isalnum( "#" ) ? "# is a " : "# is not a ", 
       "digit or a letter" );
   printf( "%s\n%s%s\n%s%s\n%s%s\n%s%s\n%s%s\n", 
       "According to isxdigit:",
       isxdigit( "F" ) ? "F is a " : "F is not a ", 
       "hexadecimal digit",
       isxdigit( "J" ) ? "J is a " : "J is not a ", 
       "hexadecimal digit",
       isxdigit( "7" ) ? "7 is a " : "7 is not a ", 
       "hexadecimal digit",
       isxdigit( "$" ) ? "$ is a " : "$ is not a ", 
       "hexadecimal digit",
       isxdigit( "f" ) ? "f is a " : "f is not a ", 
       "hexadecimal digit" );
   return 0;
}
According to isdigit:
8 is a digit
# is not a digit
According to isalpha:
A is a letter
b is a letter
& is not a letter
4 is not a letter
According to isalnum:
A is a digit or a letter
8 is a digit or a letter
# is not a digit or a letter
According to isxdigit:
F is a hexadecimal digit
J is not a hexadecimal digit
7 is a hexadecimal digit
$ is not a hexadecimal digit
f is a hexadecimal digit

Using functions islower, isupper, tolower, toupper

#include <stdio.h>
#include <ctype.h>
int main()
{ 
   printf( "%s\n%s%s\n%s%s\n%s%s\n%s%s\n\n",
           "According to islower:",
           islower( "p" ) ? "p is a " : "p is not a ",
           "lowercase letter",
           islower( "P" ) ? "P is a " : "P is not a ",
           "lowercase letter",
           islower( "5" ) ? "5 is a " : "5 is not a ",
           "lowercase letter",
           islower( "!" ) ? "! is a " : "! is not a ",
           "lowercase letter" );
   printf( "%s\n%s%s\n%s%s\n%s%s\n%s%s\n\n",
           "According to isupper:",
           isupper( "D" ) ? "D is an " : "D is not an ",
           "uppercase letter",
           isupper( "d" ) ? "d is an " : "d is not an ",
           "uppercase letter",
           isupper( "8" ) ? "8 is an " : "8 is not an ",
           "uppercase letter",
           isupper( "$" ) ? "$ is an " : "$ is not an ",
           "uppercase letter" );
   printf( "%s%c\n%s%c\n%s%c\n%s%c\n",
           "u converted to uppercase is ", toupper( "u" ),
           "7 converted to uppercase is ", toupper( "7" ),
           "$ converted to uppercase is ", toupper( "$" ),
           "L converted to lowercase is ", tolower( "L" ) );
   return 0;
}
According to islower:
p is a lowercase letter
P is not a lowercase letter
5 is not a lowercase letter
! is not a lowercase letter
According to isupper:
D is an uppercase letter
d is not an uppercase letter
8 is not an uppercase letter
$ is not an uppercase letter
u converted to uppercase is U
7 converted to uppercase is 7
$ converted to uppercase is $
L converted to lowercase is l

Using functions isspace, iscntrl, ispunct, isprint, isgraph

#include <stdio.h>
#include <ctype.h>
int main()
{
   printf( "%s\n%s%s%s\n%s%s%s\n%s%s\n\n", 
       "According to isspace:", 
       "Newline", isspace( "\n" ) ? " is a " : " is not a ",
       "whitespace character", "Horizontal tab",
       isspace( "\t" ) ? " is a " : " is not a ", 
       "whitespace character",
       isspace( "%" ) ? "% is a " : "% is not a ",
       "whitespace character" );
   printf( "%s\n%s%s%s\n%s%s\n\n", "According to iscntrl:", 
       "Newline", iscntrl( "\n" ) ? " is a " : " is not a ",
       "control character", iscntrl( "$" ) ? "$ is a " : 
       "$ is not a ", "control character" );
   printf( "%s\n%s%s\n%s%s\n%s%s\n\n", 
       "According to ispunct:",
       ispunct( ";" ) ? "; is a " : "; is not a ", 
       "punctuation character",
       ispunct( "Y" ) ? "Y is a " : "Y is not a ",
       "punctuation character",
       ispunct( "#" ) ? "# is a " : "# is not a ",
       "punctuation character" );
   printf( "%s\n%s%s\n%s%s%s\n\n", "According to isprint:",
       isprint( "$" ) ? "$ is a " : "$ is not a ", 
       "printing character", 
       "Alert", isprint( "\a" ) ? " is a " : " is not a ",
       "printing character" );
   printf( "%s\n%s%s\n%s%s%s\n",  "According to isgraph:",
       isgraph( "Q" ) ? "Q is a " : "Q is not a ",
       "printing character other than a space",
       "Space", isgraph( " " ) ? " is a " : " is not a ",
       "printing character other than a space" );
   return 0; 
}
According to isspace:
Newline is a whitespace character
Horizontal tab is a whitespace character
% is not a whitespace character
According to iscntrl:
Newline is a control character
$ is not a control character
According to ispunct:
; is a punctuation character
Y is not a punctuation character
# is a punctuation character
According to isprint:
$ is a printing character
Alert is not a printing character
According to isgraph:
Q is a printing character other than a space
Space is not a printing character other than a space