Cctype

💻️/C++ publish: true aliases:

null cssclass: null created: 2021-12-31 1945 updated: 2022-01-01 2151

The C Character Type Library

This header declares a set of functions to classify and transform individual characters.

isalpha( c )

true if alphabetic: a-z or A-Z

isalpha('x') // true
isalpha('6') // false
isalpha('!') // false

isdigit( c )

true if digit: 0-9.

isdigit('x') // false
isdigit('6') // true

isalnum( c )

Returns true if c is alphabetic or a numeric digit. Thus, returns true if either import.software.language.cpp.include-cctype (Private) or import.software.language.cpp.include-cctype (Private) would return true.

isspace( c )

true if whitespace.

isspace(' ')  // true
isspace('\n') // true
isspace('x')  // false

toupper( c )

Uppercase version

toupper('a')  // A
toupper('A')  // A
toupper('3')  // 3

tolower( c )

Lowercase version

tolower('A')  // a
tolower('a')  // a
tolower('3')  // 3

isblank()

Returns true if character c is a blank character. Blank characters include spaces and tabs.

isblank(myString[5]); // Returns true because that character is a space ' '.
isblank(myString[0]); // Returns false because 'H' is not blank.

isxdigit()

Returns true if c is a hexadecimal digit: 0-9, a-f, A-F.

isxdigit(myString[3]); // Returns true because '9' is a hexadecimal digit.
isxdigit(myString[1]); // Returns true because 'e' is a hexadecimal digit.
isxdigit(myString[6]); // Returns false because 'G' is not a hexadecimal digit.

ispunct()

Returns true if c is a punctuation character. Punctuation characters include: !"#$%&'()*+,-./:;<=>?@[\]^_{|}~

ispunct(myString[4]); // Returns true because '!' is a punctuation character.
ispunct(myString[6]); // Returns false because 'G' is not a punctuation character.