C ++中未初始化的std :: string变量的值和大小 [英] Value and size of an uninitialized std::string variable in c++

问题描述

如果这样定义一个字符串

If a string is defined like this

std::string name;

未初始化的字符串 name的值是多少，大小是多少？ p>

What will be the value of the uninitialized string "name" and what size it would be?

推荐答案

由于未初始化，因此被称为默认构造函数。然后：

Because it is not initialized, it is the default constructor that is called. Then :

空字符串构造函数（默认构造函数）：

构造一个空字符串，长度为零个字符。

Constructs an empty string, with a length of zero characters.

看看： http://www.cplusplus.com/reference/string/string/string/

编辑：
如 C ++ 11，§21.4.2/ 1 中所述：

作用：构造 basic_string 类的对象。此功能的后置条件在表63中给出。

Effects: Constructs an object of class basic_string. The postconditions of this function are indicated in Table 63.

-> Table 63
+-----------------------------------------------------------------------------+
| data()     | a non-null pointer that is copyable and can have 0 added to it |
+------------+----------------------------------------------------------------+
| size()     | 0                                                              |
+------------+----------------------------------------------------------------+
| capacity() | an unspecified value                                            |
+-----------------------------------------------------------------------------+

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