Header File ctype.h
This is a header file that contains some character conversion and testing functions.1) toupper():
To convert a given lower case English letter into corresponding uppercase letter.Syntax: d=toupper(c)
Where --> c,d = char
e.g.
c='a' --> d='A'
c='e' --> d='E'
c='G' --> d='G'
c='?' --> d='?'
2) tolower():
To convert a given upper case English letter into corresponding lower case letter.Syntax: d=tolower(c)
Where --> c,d = char
e.g.
c='A' --> d='a'
c='E' --> d='e'
c='g' --> d='g'
c='?' --> d='?'
3) isalpha():
To check whether given string contains English letter or not. If yes, then the result is non-zero (true), else 0 (false).Syntax: d=isalpha(c) --> c is char type, d is int type.
4) isdigit():
To check whether given string contains digits or not. If yes, then the result is non-zero (true), else 0 (false).Syntax: d=isdigit(c) --> c is char type, d is int type.
5) isupper():
To check whether given string contains English upper case letters or not. If yes, then the result is non-zero (true), else 0 (false).Syntax: d=isupper(c) --> c is char type, d is int type.
6) islower():
To check whether given string contains English lower case letters or not. If yes, then the result is non-zero (true), else 0 (false).Syntax: d=islower(c) --> c is char type, d is int type.
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