C <ctype.h> header

Header file <ctype.h> includes numerous standard library functions to handle characters (especially test characters). You will find various library functions defined under <ctype.h> for character handling in this chapter.

Function Description
C isalnum() checks alphanumeric character
C isalpha() checks whether a character is an alphabet or not
C iscntrl() checks control character
C isdigit() checks numeric character
C isgraph() checks graphic character
C islower() checks lowercase alphabet
C isprint() checks printable character
C ispunct() checks punctuation
C isspace() check white-space character
C isupper() checks uppercase alphabet
C isxdigit() checks hexadecimal digit character
C tolower() converts alphabet to lowercase
C toupper() converts to lowercase alphabet