Character Functions

int isalnum(int c);

• The function returns nonzero if c is alphanumeric

int isalpha(int c);

• The function returns nonzero if c is alphabetic only

int iscntrl(int c);

• The function returns nonzero if c is a control chracter

int isdigit(int c);

• The function returns nonzero if c is a numeric digit

int islower(int c); 

• The function returns nonzero if c is a lower case character.

int ispunct(int c); 

• The function returns nonzero if c is punctuation

int isspace(int c);

• The function returns nonzero if c is space character

int isupper(int c);

• The function returns nonzero if c is upper case character

int isxdigit(int c);

• The function returns nonzero if c is hexa digit

int tolower(int c);

• The function returns the corresponding lowercase letter if one exists and if isupper(c); otherwise, it returns c.

int toupper(int c);

• The function returns the corresponding uppercase letter if one exists and if islower(c); otherwise, it returns c.