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C Library Function - `isspace()`

Description

The C library function int isspace(int c) checks whether the passed character is a white-space character.

The standard white-space characters include:

' '     (0x20)    space (SPC)
'\t'    (0x09)    horizontal tab (TAB)
'\n'    (0x0a)    newline (LF)
'\v'    (0x0b)    vertical tab (VT)
'\f'    (0x0c)    feed (FF)
'\r'    (0x0d)    carriage return (CR)

Declaration

Here is the declaration for the isspace() function.

int isspace(int c);

Parameters

c -- This is the character to be checked.

Return Value

This function returns a non-zero value (true) if c is a white-space character, otherwise it returns 0 (false).

Example

The following example demonstrates the use of the isspace() function.

#include <stdio.h>
#include <ctype.h>

int main()
{
   int var1 = 't';
   int var2 = '1';
   int var3 = ' ';

   if( isspace(var1) )
   {
       printf("var1 = |%c| is a white-space character\n", var1 );
   }
   else
   {
       printf("var1 = |%c| is not a white-space character\n", var1 );
   }
   if( isspace(var2) )
   {
       printf("var2 = |%c| is a white-space character\n", var2 );
   }
   else
   {
       printf("var2 = |%c| is not a white-space character\n", var2 );
   }
   if( isspace(var3) )
   {
       printf("var3 = |%c| is a white-space character\n", var3 );
   }
   else
   {
       printf("var3 = |%c| is not a white-space character\n", var3 );
   }

   return(0);
}

Let's compile and run the above program, which will produce the following result:

var1 = |t| is not a white-space character
var2 = |1| is not a white-space character
var3 = | | is a white-space character

C Standard Library - <ctype.h>