Character Handling Library

Last time we wrapped up the topic of Pointers and Strings , today we will have a look at <cctype> which is a very important and useful library in C++.

Character Handling Library or <cctype> is a library in C++

–        It has functions to perform tests and manipulations on characters

–       You pass character as argument

•          Character represented by an int

–        char does not allow negative values

•          Characters often manipulated as ints

•          EOF usually has value -1

•   In the upcoming example you will witness the usage of:

–        isalpha( int c )

•          (All character functions take int argument)

•          Returns true if c is a letter (A-Z, a-z)

•          Returns false otherwise

–        isdigit

•          Returns true if digit (0-9)

–        isalnum

•          Returns true if letter or digit (A-Z, a-z, 0-9)

–        isxdigit

•          Returns true if hexadecimal digit (A-F, a-f, 0-9)

  

Some other functions of the character handling Library are:

–        islower

•          Returns true if lowercase letter (a-z)

–        isupper

•          Returns true if uppercase letter (A-Z)

–        tolower

•          If passed uppercase letter, returns lowercase letter

–        A to a

•          Otherwise, returns original argument

–        toupper

•          As above, but turns lowercase letter to uppercase

–        a to A

–        isspace

•          Returns true if space ' ', form feed '\f', newline '\n', carriage return '\r', horizontal tab '\t', vertical tab '\v'

–        iscntrl

•          Returns true if control character, such as tabs, form feed, alert ('\a'), backspace('\b'), carriage return, newline

–        ispunct

•          Returns true if printing character other than space, digit, or letter

•          $ # ( ) [ ] { } ; : %, etc.

–        isprint

•          Returns true if character can be displayed (including space)

–        isgraph

•          Returns true if character can be displayed, not including space

 Some of these are better explained through there usage in the following example: