C library function - isspace()



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

Standard white-space characters are −

' '   (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)


Following is the declaration for isspace() function.

int isspace(int c);


  • 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 else, zero (false).


The following example shows the usage of 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 );

Let us compile and run the above program that 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