What is isblank() in C++?
We use the isblank() function in C++ to determine if a given character is a blank character. A blank character is any of the following characters:
' ': The space character.'\t': The tab character.
Library
To use the isblank() function, include the following library:
#include <cctype>
Declaration
The isblank() function is declared as follows:
int isblank(int c);
c: The ASCII value of the character being checked.
Note: If
cis not anunsigned charorEOF, the behavior of theisblank()function is undefined.
Return value
- The
isblank()function returns a non-zero value ifcis a blank. - The
isblank()function returns0ifcis not a blank.
Code
Example 1
Consider the code snippet below, which demonstrates the use of the isblank() function.
#include <cctype>#include <iostream>using namespace std;int main(){char c1 = 'a';char c2 = ' ';cout<<"'"<<c1<<"' is blank: "<<isblank(c1)<<endl;cout<<"'"<<c2<<"' is blank: "<<isblank(c2)<<endl;return 0;}
Explanation
Two characters c1 and c2 are declared in lines 7-8. c1 is not a blank and c2 is a blank.
- line 10: We use the
isblank()function in line 10 to check whetherc1is a blank. Theisblank()function returns 0, which means thatc1is not a blank. - line 11: We use the
isblank()function in line 11 to check whetherc2is a blank. Theisblank()function returns a non-zero value, which means thatc2is a blank.
Code 2
Consider the code snippet below, which uses the isblank() function to remove the blanks from other characters in a string.
#include <cctype>#include <cstring>#include <iostream>using namespace std;int main(){char str[] = "H el lo w o r d!! ";int len = strlen(str);char withoutBlanks[len];int blankCount = 0;int ind = 0 ;for(int i = 0; i < len; i++){if( isblank(str[i])==0 ){withoutBlanks[ind] = str[i];ind++;}else{blankCount++;}}withoutBlanks[ind] = '\0';cout<<"string = "<<str<<endl;cout<<"string without blanks = "<<withoutBlanks<<endl;cout<<"number of blanks in string = "<<blankCount<<endl;return 0;}
Explanation
- line 8: A string
stris declared that contains both blank and non-blank characters. - line 10: A string
withoutBlanksis declared that will contain the non-blank characters ofstr. - line 11: A variable
blankCountis declared that will contain the count of the number of blank characters ofstr. - lines 14-17: Loop over the characters of
strsuch that if a character is a non-blank, it is copied the character inwithoutBlanks. If a character is a blank, add one toblankCount.
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