C – islower() function

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  • islower( ) function in C language checks whether given character is lower case or not. Syntax for islower( ) function is given below.

int islower( int x );

Example program for islower() function in C:

#include <stdio.h>

int main()
{
   char ch;
   printf("Enter any charactern");
   scanf("%c", &ch);

   if ( islower ( ch ) )
   printf ( "nEntered character is lower case character") ;
   else
   printf("nEntered character is not lower case character");
}

Output:

Enter any character
a
Entered character is lower case character

..

Other Int, Char validation functions in C language:

  • All “int, char validation functions” used in C language are given below. “ctype.h” header files support all these functions in C language.
  • Click on each function name below for detail description and example programs.
S.no Function Description
1 isalpha() checks whether character is alphabetic
2 isdigit() checks whether character is digit
3 isalnum() checks whether character is alphanumeric
4 isspace() checks whether character is space
5 islower() checks whether character is lower case
6 isupper() checks whether character is upper case
7 isxdigit() checks whether character is hexadecimal
8 iscntrl() checks whether character is a control character
9 isprint() checks whether character is a printable character
10 ispunct() checks whether character is a punctuation
11 isgraph() checks whether character is a graphical character
12 tolower() checks whether character is alphabetic & converts to lower case
13 toupper() checks whether character is alphabetic & converts to upper case

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