_tolower()               Convert 'c' to Lowercase
 
 #include   <ctype.h>
 
 int        _tolower(c);
 int        c;                           Character to be converted
 
    The _tolower() macro converts 'c' to lowercase. It should only to be
    used when 'c' is known to be an uppercase letter, as the result is
    undefined otherwise.
 
    Returns:    The converted character 'c'. There is no error return.
 
      Notes:    Use tolower() to convert a character that is not
                necessarily an uppercase letter.
 
  -------------------------------- Example ---------------------------------
 
    The following statements convert a string to lowercase before
    printing it.
 
         #include <ctype.h>
         #include <stdio.h>
 
         char string[15] = "ALPHABET";
         int x;
 
         main()
         {
             for (x = 0; x < strlen(string); x++)
                 printf("%c",_tolower(string[x]));
             printf("\n");
         }

Seealso:


 islower() 
 isupper() 
 tolower()