---
name: "std::wstring_convert"
section: "3cxx"
platform: "linux"
package: "libstdc++-12-doc"
version: "12.4.0-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/std::wstring_convert/3cxx"
---

# std::wstring\_convert(3cxx)

String conversions.

## NAME

std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \> - String conversions.

## SYNOPSIS

`#include <locale>`

### Public Types

**typedef** **basic\_string**\< char, **char\_traits**\< char \>, **\_Byte\_alloc** \> **byte\_string**\
 **typedef** wide\_string::traits\_type::int\_type **int\_type**\
 **typedef** \_Codecvt::state\_type **state\_type**\
 **typedef** **basic\_string**\< **\_Elem**, **char\_traits**\< **\_Elem** \>, **\_Wide\_alloc** \> **wide\_string**\

### Public Member Functions

**wstring\_convert** ()\
 Default constructor.  **wstring\_convert** (\_Codecvt \***\_\_pcvt**)\
 **wstring\_convert** (\_Codecvt \***\_\_pcvt**, state\_type **\_\_state**)\
 **wstring\_convert** (const **byte\_string** &**\_\_byte\_err**, const **wide\_string** &**\_\_wide\_err**=**wide\_string**())\
 **wstring\_convert** (const **wstring\_convert** &)=**delete**\
 size\_t **converted** () const noexcept\
 The number of elements successfully converted in the last conversion.  **wstring\_convert** & **operator=** (const **wstring\_convert** &)=**delete**\
 state\_type **state** () const\
 The final conversion state of the last conversion.

**wide\_string** **from\_bytes** (char **\_\_byte**)\
 Convert from bytes.  **wide\_string** **from\_bytes** (const char \***\_\_ptr**)\
 Convert from bytes.  **wide\_string** **from\_bytes** (const **byte\_string** &**\_\_str**)\
 Convert from bytes.  **wide\_string** **from\_bytes** (const char \*\_\_first, const char \*\_\_last)\
 Convert from bytes.

**byte\_string** **to\_bytes** (**\_Elem** **\_\_wchar**)\
 Convert to bytes.  **byte\_string** **to\_bytes** (const **\_Elem** \***\_\_ptr**)\
 Convert to bytes.  **byte\_string** **to\_bytes** (const **wide\_string** &**\_\_wstr**)\
 Convert to bytes.  **byte\_string** **to\_bytes** (const **\_Elem** \*\_\_first, const **\_Elem** \*\_\_last)\
 Convert to bytes.

## Detailed Description

### template\<typename \_Codecvt, typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\>

class std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>"String conversions.

## Constructor & Destructor Documentation

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::wstring\_convert ()` [inline]`

Default constructor.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::wstring\_convert (\_Codecvt \* \_\_pcvt)` [inline]`, ` [explicit]`

Constructor.

**Parameters**

*\_\_pcvt* The facet to use for conversions.

Takes ownership of `__pcvt` and will delete it in the destructor.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::wstring\_convert (\_Codecvt \* \_\_pcvt, state\_type \_\_state)` [inline]`

Construct with an initial converstion state.

**Parameters**

*\_\_pcvt* The facet to use for conversions. \
 *\_\_state* Initial conversion state.

Takes ownership of `__pcvt` and will delete it in the destructor. The object's conversion state will persist between conversions.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::wstring\_convert (const byte\_string & \_\_byte\_err, const wide\_string & \_\_wide\_err = wide\_string`()`)` [inline]`, ` [explicit]`

Construct with error strings.

**Parameters**

*\_\_byte\_err* A string to return on failed conversions. \
 *\_\_wide\_err* A wide string to return on failed conversions.

## Member Function Documentation

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> size\_t std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::converted () const` [inline]`, ` [noexcept]`

The number of elements successfully converted in the last conversion.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> wide\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes (char \_\_byte)` [inline]`

Convert from bytes.

References **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes()**.

Referenced by **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes()**, **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes()**, and **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes()**.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> wide\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes (const byte\_string & \_\_str)` [inline]`

Convert from bytes.

References **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes()**.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> wide\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes (const char \* \_\_first, const char \* \_\_last)` [inline]`

Convert from bytes.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> wide\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes (const char \* \_\_ptr)` [inline]`

Convert from bytes.

References **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::from\_bytes()**.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> state\_type std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::state () const` [inline]`

The final conversion state of the last conversion.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> byte\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes (\_Elem \_\_wchar)` [inline]`

Convert to bytes.

References **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes()**.

Referenced by **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes()**, **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes()**, and **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes()**.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> byte\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes (const \_Elem \* \_\_first, const \_Elem \* \_\_last)` [inline]`

Convert to bytes.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> byte\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes (const \_Elem \* \_\_ptr)` [inline]`

Convert to bytes.

References **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes()**.

### template\<typename \_Codecvt , typename \_Elem = wchar\_t, typename \_Wide\_alloc = allocator\<\_Elem\>, typename \_Byte\_alloc = allocator\<char\>\> byte\_string std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes (const wide\_string & \_\_wstr)` [inline]`

Convert to bytes.

References **std::wstring\_convert\< \_Codecvt, \_Elem, \_Wide\_alloc, \_Byte\_alloc \>::to\_bytes()**.

## Author

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