I am trying to figure out how to check if a character is equal to white-space in C. I know that tabs are '\t'
and newlines are '\n'
, but I want to be able to check for just a regular normal space (from the space-bar) inside of an if
statement.
Does anybody know what is the character for this?
This question is related to
c
whitespace
space
#include <stdio.h>
main()
{
int c,sp,tb,nl;
sp = 0;
tb = 0;
nl = 0;
while((c = getchar()) != EOF)
{
switch( c )
{
case ' ':
++sp;
printf("space:%d\n", sp);
break;
case '\t':
++tb;
printf("tab:%d\n", tb);
break;
case '\n':
++nl;
printf("new line:%d\n", nl);
break;
}
}
}
The ASCII value of Space
is 32. So you can compare your char to the octal value of 32 which is 40 or its hexadecimal value which is 20.
if(c == '\40')
{ ... }
or
if(c == '\x20')
{ ... }
Any number after the \
is assumed to be octal, if the character just after \
is not x
, in which case it is considered to be a hexadecimal.
make use of isspace function .
The C library function int isspace(int c) checks whether the passed character is white-space.
sample code:
int main()
{
char var= ' ';
if( isspace(var) )
{
printf("var1 = |%c| is a white-space character\n", var );
}
/*instead you can easily compare character with ' '
*/
}
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)
source : tutorialpoint
The character representation of a Space is simply ' '
.
void foo (const char *s)
{
unsigned char c;
...
if (c == ' ')
...
}
But if you are really looking for all whitespace, then C has a function (actually it's often a macro) for that:
#include <ctype.h>
...
void foo (const char *s)
{
char c;
...
if (isspace(c))
...
}
You can read about isspace
here
If you really want to catch all non-printing characters, the function to use is isprint
from the same library. This deals with all of the characters below 0x20 (the ASCII code for a space) and above 0x7E (0x7f is the code for DEL, and everything above that is an extension).
In raw code this is equivalent to:
if (c < ' ' || c >= 0x7f)
// Deal with non-printing characters.
No special escape sequence is required: you can just type the space directly:
if (char_i_want_to_test == ' ') {
// Do something because it is space
}
In ASCII, space is code 32, so you could specify space by '\x20'
or even 32
, but you really shouldn't do that.
Aside: the word "whitespace" is a catch all for space, tab, newline, and all of that. When you're referring specifically to the ordinary space character, you shouldn't use the term.
To check a space symbol you can use the following approach
if ( c == ' ' ) { /*...*/ }
To check a space and/or a tab symbol (standard blank characters) you can use the following approach
#include <ctype.h>
//...
if ( isblank( c ) ) { /*...*/ }
To check a white space you can use the following approach
#include <ctype.h>
//...
if ( isspace( c ) ) { /*...*/ }
Source: Stackoverflow.com