SAS/C Library Reference, Vol. 1

tolower -- Translate Uppercase Character to Lowercase

SYNOPSIS

 #include <ctype.h>

 int tolower(int c);

DESCRIPTION

tolower translates an uppercase character to the corresponding lowercase character. The argument must either be a char value or EOF. The mapping of uppercase to lowercase characters is locale dependent.

RETURN VALUE

If the argument is an uppercase character, the corresponding lowercase character is returned; otherwise, the argument value is returned.

IMPLEMENTATION

tolower is implemented by the compiler as a built-in function, unless you use the name tolower with #undef.

EXAMPLE

  #include <ctype.h>
  #include <stdio.h>

  #define MAX 40

  main()
  {
     char *str, *ptr;
     char input[MAX];

     puts("Enter a string of uppercase characters (maximum of 40):");
     str = gets(input);
     ptr = str;

        /* Translate all uppercase characters in a string to      */
        /*  lowercase characters.                                 */
     while (*str) {
        *str = tolower(*str);

           /* Increment outside of macro for maximum portability. */
        str++;
     }
     printf("%sn", ptr);
  }

RELATED FUNCTIONS

islower, memlwr, strlwr, toupper