towlower() function in C/C++

The towlower() is a built-in function in C/C++ which converts the given wide character into lowercase. It is defined within the cwctype header file of C++.

• It is a function in header file , so it is mandatory to use this header file if using this function
• It is the wide-character equivalent of the towlower() function.

Syntax:

wint_t towlower( wint_t ch )

Parameter: The function accepts a single mandatory parameter ch which specifies the wide character which we have to convert into lowercase. Return Value: The function returns the lowercase equivalent to c, if such value exists, or c (unchanged) otherwise. The value is returned as a wint_t value that can be implicitly casted to wchar_t. Below programs illustrates the above function. Program 1: 

CPP

// Program to illustrate
// towlower() function
#include <cwchar>
#include <cwctype>
#include <iostream>
using namespace std;
int main()
{

    wchar_t str[] = L"GeeksforGeeks";
    wcout << L"The lowercase version of \""
          << str << L"\" is ";

    for (int i = 0; i < wcslen(str); i++)
        // Function to convert the character
        // into the lowercase version, if exists
        putwchar(towlower(str[i]));

    return 0;
}

Output:

The lowercase version of "GeeksforGeeks" is geeksforgeeks

Program 2: 

CPP

// Program to illustrate
// towlower() function
#include <cwchar>
#include <cwctype>
#include <iostream>
using namespace std;
int main()
{

    wchar_t str[] = L"hello Ishwar 123!@#";
    wcout << L"The lowercase version of \""
          << str << L"\" is ";

    for (int i = 0; i < wcslen(str); i++)
        // Function to convert the character
        // into the lowercase version, if exists
        putwchar(towlower(str[i]));

    return 0;
}

Output:

The lowercase version of "hello Ishwar 123!@#" is hello ishwar 123!@#