In this article, you will learn about different C programming character handling library functions that are used for character processing.

As we know that characters are the fundamental building blocks of every program.
A character constant is represented as a character in a single quote. The value of character constant is an integer.
For example, a is represented as 'a' which is actually the integer value equal to 97 in ASCII.
Similarly, '\n' represents the integer value of newline equal to 10 in ASCII.
C provides standard character handling library <ctype.h>.
We should include character handling library i.e. <ctype.h> for using different character handling function.
This header include various useful functions for performing tests and manipulations of character data in C programming.
The function in <ctype.h> recieves an unsigned char represented as int or EOF as argument.
In C programming, character is a one byte integer.
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C programming character library functions with description |
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| int islower( int ch ); It returns a true if ch is a lowercase letter and 0 otherwise. |
| int isupper( int ch ); It returns a true value if ch is a uppercase and 0 therwise. |
| int tolower( int ch ); This function converts uppercase letter into lowercase letter. |
| int toupper( int ch ); This function converts lowercase letter into uppercase letter. |
| int isblank( int ch ); This function checks whether ch is a blank character or not. |
| int isdigit( int ch ); This function checks whether ch is a digit or not. |
| int isalpha int ch ); This function checks whether ch is a letter or not. |
| int isalnum( int ch ); This function returns a 1 if ch is a digit or a letter and 0 otherwise. |
| int isxdigit( int ch ); This function checks if ch is a hexadecimal digit or not. |
| int isspace( int ch ); This function checks if ch is a whitespace character or not. |
| int isgraph( int ch ); This function checks if ch is a printing character other than a space or not. |
| int iscntrl( int ch ); This function checks if ch is a control character or not. |
| int isprint( int ch ); This function checks if ch is a printing character including a space or not. |
| int ispunct( int ch ); This function checks if ch is a printing character other than a digit, a space, a letter or not. |