C++ cuchar::mbrtoc16() Function

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The std::cuchar::mbrtoc16() function in C++, is used to convert a multibyte character sequences into 16-bit wide character. This function takes a multibyte sequence, a mbstate_t object to track state, and the current conversion context.

It returns the numbers of bytes processed, a decoded char16_t character, or indicates errors like incomplete sequences.

Syntax

Following is the syntax for std::cuchar::mbrtoc16() function.

size_t mbrtoc16 ( char16_t * pc16, const char * pmb, size_t max, mbstate_t * ps);

Parameters

• pc16 − It indicates a pointer to an object of type char16_t.
• pmb − It indicates the pointer to the first byte of a multibyte character.
• max − It indicates a maximum number of bytes to read from pmb.
• ps − It indicates a pointer to a mbstate_t object that defines a conversion state.

Return value

This function returns the number bytes from pmb used to produce the 16-bit character.

Example 1

Let's look at the following example, where we are going to perform the basic conversion.

#include <cuchar>
#include <iostream>
int main() {
   const char * a = "X";
   char16_t b;
   mbstate_t c = {};
   std::size_t result = std::mbrtoc16( & b, a, 1, & c);

   if (result != static_cast < std::size_t > (-1)) {
      std::wcout << L " Result : " << static_cast < wchar_t > (b) << L '\n';
   } else {
      std::cerr << "Conversion failed!\n";
   }
   return 0;
}

Output

Output of the above code is as follows −

Result : X

Example 2

Consider the following example, where we are going to perform the conversion of the multibyte string.

#include <cuchar>
#include <iostream>
int main() {
   const char * a = "TP";
   char16_t b;
   mbstate_t c = {};
   for (size_t x = 0; x < 2; ++x) {
      std::size_t y = std::mbrtoc16( & b, & a[x], 1, & c);
      if (y == 0) {
         break;
      }
      std::wcout << L "Converted : " << static_cast < wchar_t > (b) << L '\n';
   }
   return 0;
}

Output

Following is the output of the above code −

Converted : T
Converted : P

Example 3

In the following example, we are going to consider the invalid multibyte and perform the conversion and observe the output.

#include <iostream>
#include <cuchar>
#include <cwchar>
int main() {
   const char * x = "\xAB";
   char16_t y;
   mbstate_t z = {};
   size_t a = mbrtoc16( & y, x, 1, & z);
   if (a == (size_t) - 1) {
      std::cout << "Encoding error detected.\n";
   } else if (a == (size_t) - 2) {
      std::cout << "Incomplete sequence.\n";
   } else {
      std::cout << "Converted : " << static_cast < char > (y) << "\n";
   }
   return 0;
}

Output

If we run the above code it will generate the following output −

Encoding error detected.