mbsinit() Function in C/C++

The mbsinit() is an inbuilt function in C++ which is used to check whether ps(passed as a parameter to this function) points to a mbstate_t object that describes an initial conversion state. This function returns non-zero for any mbstate_t object representing an initial state, or if ps is a null pointer. 
The state pointed by ps can be set to the initial state by calling : 

// ps points now to a zero-valued object
memset (ps, 0, sizeof(*ps));

Syntax :

int mbsinit( const mbstate_t* ps)

Parameter : The function accepts one parameter as described below: 

• ps :Pointer to an mbstate_t object

Return Value : The function returns two value as follows: 

• 0 if ps is not a null pointer and doesn’t represent the initial conversion state.
• Nonzero if ps is a null pointer or represents the initial conversion state.

Below programs illustrate the above function: 
Program 1 : 

CPP

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

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

// function to check if the object describes
// the initial conversion state
void checkfor(mbstate_t ps)
{
    // (mbstate_t) Type that holds the information necessary
    // to maintain the state when converting between
    // sequences of multibyte characters and
    // wide characters (either way).

    int func = mbsinit(&ps);

    if (func)
        cout<<"The conversion state is initial"
                                 <<" conversion state\n";

    else
        cout<<"The conversion state is not initial"
                                    <<" conversion state";
}

// Driver code
int main()
{
    setlocale(LC_ALL, "en_US.utf8");

    // initializing the string
    char str[] = "\u00df";

    // initial state
    mbstate_t ps = mbstate_t();

    // check if ps is liknked to
    // initial conversion state
    checkfor(ps);

    mbrlen(str, 1, &ps);

    // check if, after getting the
    // length of multibyte character
    checkfor(ps);

    return 0;
}

Output:

The conversion state is initial conversion state
The conversion state is not initial conversion state

Program 2 : 

CPP

// C++ program to illustrate
// mbsinit() function
// with empty string

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

// function to check if
// object describes the initial conversion state
void checkfor(mbstate_t ps)
{
    // (mbstate_t) Type that holds the information necessary
    // to maintain the state when converting between
    // sequences of multibyte characters and
    // wide characters (either way).

    int func = mbsinit(&ps);

    if (func)
        cout << "the conversion state is initial"
                                <<" conversion state\n";

    else
        cout << "the conversion state is not initial"
                                <<" conversion state";
}

// Driver code
int main()
{
    setlocale(LC_ALL, "en_US.utf8");

    // initializing the string
    char str[] = "";

    // initial state
    mbstate_t ps = mbstate_t();

    // check if ps is liknked to
    // initial conversion state
    cout << "After ps is initialized, ";
    checkfor(ps);

    mbrlen(str, 0, &ps);

    // check if, after getting the
    // length of multibyte character
    cout << "After performing some task, ";
    checkfor(ps);

    return 0;
}

Output:

After ps is initialized, the conversion state is initial conversion state
After performing some task, the conversion state is initial conversion state