From:http://www.cplusplus.com/reference/clibrary/cctype/tolower/
#include <ctype.h>
or
#include <cctype>
tolower
int tolower(int c);
Convert uppercase letter to lowercase
Converts parameter c to its lowercase equivalent if c is an uppercase letter and has a lowercase equivalent.
If no such conversion is possible, the value returned is c unchanged.
Notice that what is considered a letter may depend on the locale being used;
In the default C locale, an uppercase letter is any of: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z,
which translate respectively to: a b c d e f g h i j k l m n o p q r s t u v w x y z.
In C++, a locale-specific template version of this function (tolower) exists in header <locale>.
Parameters
C
Uppercase letter character to be converted, casted to an int, or EOF.
Return Value
The lowercase equivalent to c, if such value exists,
or c (unchanged) otherwise.
The value is returned as an int value that can be implicitly casted to char.
Example
/* tolower example */
#include <stdio.h>
#include <ctype.h>
int main(void)
{
int i = 0;
char str[] = "Test String.\n";
char c;
while(str[i])
{
c = str[i];
putchar(tolower(c));
i++;
}
return 0;
}
Output:
test string.
