wctrans() function in C/C++

This wctrans() in C/C++ is specified in header file cwctype.h and returns a value of type wctrans_t that corresponds to the transformation. A specific locale can accept multiple transformations for characters. Some following transformation are recognized as follows : 

• “tolower” -> to lowercase | towlower
• “toupper” -> to uppercase | towupper

Syntax: 

wctrans_t wctrans( const char* string )

Parameters: The function accepts one mandatory parameter string which specifies a string identifying a character transformation.
Return value : The function returns two value as below: 

• If current locale doesn’t provide a mapping then it returns zero.
• Otherwise, It returns object that can be used with towctrans() for mapping wide characters.

Below programs illustrate the above function: 
Program 1 : 

CPP

// C++ program to illustrate
// towctrans() function

#include <bits/stdc++.h>
using namespace std;

int main()
{
    // initialize the string
    wchar_t string[] = L"GeeksForGeeks";
    wcout << L"Initial string -> " << string << endl;

    wctype_t first = wctype("lower");
    wctype_t second = wctype("upper");

    // traverse each character and convert
    // lower case to upper and upper to lower
    for (int i = 0; i < wcslen(string); i++) {
        if (iswctype(string[i], first))
            string[i] = towctrans(string[i], wctrans("toupper"));
        else if (iswctype(string[i], second))
            string[i] = towctrans(string[i], wctrans("tolower"));
    }

    // print the string after transformation
    wcout << L"After transformation -> " << string << endl;

    return 0;
}

Output:

Initial string -> GeeksForGeeks
After transformation -> gEEKSfORgEEKS

Program 2 : 

CPP

// C++ program to illustrate
// towctrans() function

#include <bits/stdc++.h>
using namespace std;

int main()
{
    // initialize the string
    wchar_t string[] = L"gfg";
    wcout << L"Initial string -> " << string << endl;

    wctype_t first = wctype("lower");
    wctype_t second = wctype("upper");

    // traverse each character and convert
    // lower case to upper and upper to lower
    for (int i = 0; i < wcslen(string); i++) {
        if (iswctype(string[i], first))
            string[i] = towctrans(string[i], wctrans("toupper"));
        else if (iswctype(string[i], second))
            string[i] = towctrans(string[i], wctrans("tolower"));
    }

    // print the string after transformation
    wcout << L"After transformation -> " << string << endl;

    return 0;
}

Output:

Initial string -> gfg
After transformation -> GFG