---
description: "Learn more about: <string>"
title: "<string>"
ms.date: "11/04/2016"
f1_keywords: ["<string>"]
helpviewer_keywords: ["string header"]
ms.assetid: a2fb9d00-d7ae-4170-bfea-2dc337aa37cf
---
# `<string>`

Defines the container class template `basic_string` and various supporting templates.

For more information about `basic_string`, see [`basic_string` Class](../standard-library/basic-string-class.md)

## Syntax

```cpp
#include <string>
```

## Remarks

The C++ language and the C++ Standard Library support two types of strings:

- Null-terminated character arrays often referred to as C strings.

- class template objects, of type `basic_string`, that handle all **`char`**-like template arguments.

### Typedefs

|Type name|Description|
|-|-|
|[`string`](../standard-library/string-typedefs.md#string)|A type that describes a specialization of the class template `basic_string` with elements of type **`char`** as a `string`.|
|[`wstring`](../standard-library/string-typedefs.md#wstring)|A type that describes a specialization of the class template `basic_string` with elements of type **`wchar_t`** as a `wstring`.|
|[`u16string`](../standard-library/string-typedefs.md#u16string)|A type that describes a specialization of the class template `basic_string` based on elements of type **`char16_t`**.|
|[`u32string`](../standard-library/string-typedefs.md#u32string)|A type that describes a specialization of the class template `basic_string` based on elements of type **`char32_t`**.|

### Operators

|Operator|Description|
|-|-|
|[`operator+`](../standard-library/string-operators.md#op_add)|Concatenates two string objects.|
|[`operator!=`](../standard-library/string-operators.md#op_neq)|Tests if the string object on the left side of the operator is not equal to the string object on the right side.|
|[`operator==`](../standard-library/string-operators.md#op_eq_eq)|Tests if the string object on the left side of the operator is equal to the string object on the right side.|
|[`operator<`](../standard-library/string-operators.md#op_lt)|Tests if the string object on the left side of the operator is less than to the string object on the right side.|
|[`operator<=`](../standard-library/string-operators.md#op_lt_eq)|Tests if the string object on the left side of the operator is less than or equal to the string object on the right side.|
|[`operator<<`](../standard-library/string-operators.md#op_lt_lt)|A template function that inserts a string into the output stream.|
|[`operator>`](../standard-library/string-operators.md#op_gt)|Tests if the string object on the left side of the operator is greater than to the string object on the right side.|
|[`operator>=`](../standard-library/string-operators.md#op_gt_eq)|Tests if the string object on the left side of the operator is greater than or equal to the string object on the right side.|
|[`operator>>`](../standard-library/string-operators.md#op_gt_gt)|A template function that extracts a string from the input stream.|

### Specialized Template Functions

|Name|Description|
|-|-|
|`hash`|Produces a hash of a string.|
|[`swap`](../standard-library/string-functions.md#swap)|Exchanges the arrays of characters of two strings.|
|[`stod`](../standard-library/string-functions.md#stod)|Converts a character sequence to a **`double`**.|
|[`stof`](../standard-library/string-functions.md#stof)|Converts a character sequence to a **`float`**.|
|[`stoi`](../standard-library/string-functions.md#stoi)|Converts a character sequence to an **`int`**.|
|[`stold`](../standard-library/string-functions.md#stold)|Converts a character sequence to a **`long double`**.|
|[`stoll`](../standard-library/string-functions.md#stoll)|Converts a character sequence to a **`long long`**.|
|[`stoul`](../standard-library/string-functions.md#stoul)|Converts a character sequence to an **`unsigned long`**.|
|[`stoull`](../standard-library/string-functions.md#stoull)|Converts a character sequence to an **`unsigned long long`**.|
|[`to_string`](../standard-library/string-functions.md#to_string)|Converts a value to a `string`.|
|[`to_wstring`](../standard-library/string-functions.md#to_wstring)|Converts a value to a wide string.|

### Functions

|Function|Description|
|-|-|
|[`getline` Template](../standard-library/string-functions.md#getline)|Extract a `string`, line by line, from the input stream.|

### Classes

|Class|Description|
|-|-|
|[`basic_string` Class](../standard-library/basic-string-class.md)|A class template that describes objects that can store a sequence of arbitrary character-like objects.|
|[`char_traits` Struct](../standard-library/char-traits-struct.md)|A class template that describes attributes associated with a character of type `CharType`|

### Specializations

|Name|Description|
|-|-|
|[`char_traits<char>` Struct](../standard-library/char-traits-char-struct.md)|A struct that is a specialization of the template struct `char_traits<CharType>` to an element of type **`char`**.|
|[`char_traits<wchar_t>` Struct](../standard-library/char-traits-wchar-t-struct.md)|A struct that is a specialization of the template struct `char_traits<CharType>` to an element of type **`wchar_t`**.|
|[`char_traits<char16_t>` Struct](../standard-library/char-traits-char16-t-struct.md)|A struct that is a specialization of the template struct `char_traits<CharType>` to an element of type **`char16_t`**.|
|[`char_traits<char32_t>` Struct](../standard-library/char-traits-char32-t-struct.md)|A struct that is a specialization of the template struct `char_traits<CharType>` to an element of type **`char32_t`**.|

## Requirements

- **Header:** `<string>`

- **Namespace:** std

## See also

[Header Files Reference](../standard-library/cpp-standard-library-header-files.md)\
[Thread Safety in the C++ Standard Library](../standard-library/thread-safety-in-the-cpp-standard-library.md)