tolower - Convert uppercase letters to lowercase

Definition	#include <ctype.h> int tolower(int c); tolower converts the uppercase letter c (from the EBCDIC character set) to the corresponding lowercase letter.
Return val.	The lowercase letter corresponding to c
		if c is an uppercase letter.
	c unchanged	if c is not an uppercase letter.
Note	tolower is implemented both as a macro and as a function (see section “Functions and macros”).
Example	The following program reads a string and converts the characters first to lowercase letters and then to uppercase letters. Characters that are neither uppercase nor lowercase letters (digits, special characters, etc.) remain unchanged. #include <ctype.h> #include <stdio.h> int main(void) { int i; char s[81]; printf("Please enter a string (max. 80 characters)\n"); scanf("%s", s); printf("And now everything in lowercase letters \n"); for (i=0; s[i] != '\0'; ++i) if (isupper(s[i])) printf("%c", tolower(s[i])); else printf("%c", s[i]); printf("\n And in uppercase letters \n"); for (i=0; s[i] != '\0'; ++i) if (islower(s[i])) printf("%c", toupper(s[i])); else printf("%c", s[i]); printf("\n"); return 0; }
See also	strlower, strupper, toupper, toascii, toebcdic, towlower