一个std :: string包含嵌入的null？ [英] Can a std::string contain embedded nulls?

问题描述

对于常规C字符串，一个空字符'\0'表示数据的结尾。

std :: string ，我可以有一个带有嵌入空字符的字符串吗？

解决方案

是的，您可以在 std :: string 中嵌入null。

示例：

  std :: string s; 
 s.push_back（'\0'）; 
 s.push_back（'a'）; 
 assert（s.length（）== 2）; 
  

注意： std :: string c_str（）成员将总是在返回的char缓冲区附加一个空字符;但是， std :: string 的 data（）成员可以或不可以在返回的字符

有一件事要注意：不要在RHS上使用 operator + = 和 char * 。

例如：

  std :: string s =hello; 
 s + =\0world; 
 assert（s.length（）= 5）; 
  

正确的方式：

  std :: string s =hello; 
 s + = std :: string（\0world，6）; 
 assert（s.length（）== 11）; 
  

存储更常见的二进制数据以使用std :: vector

一般来说，使用 std :: vector 来存储任意二进制数据更为常见。

  std :: vector< char> f 
 buf.resize（1024）; 
 char * p =& buf.front（）; 
  

这可能更常见，因为 std :: string 使用& buf.front（）可以直接修改缓冲区的内容。

For regular C strings, a null character '\0' signifies the end of data.

What about std::string, can I have a string with embedded null characters?

解决方案

Yes you can have embedded nulls in your std::string.

Example:

std::string s;
s.push_back('\0');
s.push_back('a');
assert(s.length() == 2);

Note: std::string's c_str() member will always append a null character to the returned char buffer; However, std::string's data() member may or may not append a null character to the returned char buffer.

Be careful of operator+=

One thing to look out for is to not use operator+= with a char* on the RHS. It will only add up until the null character.

For example:

std::string s = "hello";
s += "\0world";
assert(s.length() == 5);

The correct way:

std::string s = "hello";
s += std::string("\0world", 6);
assert(s.length() == 11);

Storing binary data more common to use std::vector

Generally it's more common to use std::vector to store arbitrary binary data.

std::vector<char> buf;
buf.resize(1024);
char *p = &buf.front();

It is probably more common since std::string's data() and c_str() members return const pointers so the memory is not modifiable. with &buf.front() you are free to modify the contents of the buffer directly.

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