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- The C Standard Library
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C Library - isspace() function
The C library isspace() function checks whether the passed character is white-space.
This function is a part of the C Standard Library, included in the <ctype.h> header.
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)
Syntax
Following is the C library syntax of the isspace() function −
int isspace(int c);
Parameters
This function accepts a single parameter −
c − This is the character to be checked, passed as an int. The value of c should be representable as an unsigned char or be equal to the value of EOF.
Return Value
The isspace(int c) function returns a non-zero value (true) if the character is a whitespace character. Otherwise, it returns zero (false). The whitespace characters checked by isspace include −
- Space (' ')
- Form feed ('\f')
- Newline ('\n')
- Carriage return ('\r')
- Horizontal tab ('\t')
- Vertical tab ('\v')
Example 1: Checking different input as whitespace
A character 't', a number '1' and a space '' are checked for whitespace recognition using 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); }
Output
The above code produces following result−
var1 = |t| is not a white-space character var2 = |1| is not a white-space character var3 = | | is a white-space character
Example 2: Newline Character
This example checks if the newline character ('\n') is a whitespace character. Since it is, the function returns true.
#include <stdio.h> #include <ctype.h> int main() { char ch = '\n'; if (isspace(ch)) { printf("The character is a whitespace character.\n"); } else { printf("The character is not a whitespace character.\n"); } return 0; }
Output
After execution of above code, we get the following result −
The character is a whitespace character.