< cstring>和< string> [英] Difference between <cstring> and <string>

问题描述

今天早些时候（实际上是昨天由于我的时区）我正在尝试使用 Visual Studio 2012 在Interview Street的C ++编程面试（使用 g ++ ）。

简而言之，当我使用

时遇到了几个编译错误 ¹ 。

  #include< cstring> 
 

这是由框架代码提供的问题之一，然后转到

  #include< string> 
  

所有编译错误在神奇地消失。

然而，在提交到采访街，我不得不加上 c

这是我第一次被非标准化的东西....

我的问题是：< string> 和< cstring> 半小时？

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¹
$ b

Visual Studio 2012的一个错误，如果使用< cstring> 是：

< >

错误C2338：C ++标准不为此类型提供散列。

$ b

c：\program files（x86）\microsoft visual studio 11.0 \vc\include\xstddef

可能 string 为 unordered_map

如果使用< string> ，g ++会产生一个错误：

'strlen'未在此范围内声明

解决方案>

cstring 头提供了处理C风格字符串 - 以null结尾的字符数组的函数。这包括 strlen 和 strcpy 的函数。它是C的经典 string.h 头文件的C ++版本。

string 头提供 std :: string 类及相关函数和运算符。

头部具有相似的名称，但它们之间不是真正的相关。它们涵盖单独的任务。

Earlier today (actually yesterday due to my time-zone) I was attempting a programming interview using Visual Studio 2012 for C++ on Interview Street (which uses g++).

To be brief, I came across several compilation errors¹ when I was using

#include <cstring>

which was provided by the skeleton code in one of the question, and after turning to

#include <string>

all compilation errors magically disappeared.

However, upon submission to Interview Street, I had to add c back; otherwise I got compilation errors.

It was the first time I was bitten by non-standardization....

My question is: what inside <string> and <cstring> took me (precious) more than half an hour?

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¹ For anyone who is curious:

One error by Visual Studio 2012 if using <cstring> is:

error C2338: The C++ Standard doesn't provide a hash for this type.

in

c:\program files (x86)\microsoft visual studio 11.0\vc\include\xstddef

possibly for string as key in unordered_map

One error by g++ if using <string> is:

'strlen' was not declared in this scope

解决方案

The cstring header provides functions for dealing with C-style strings — null-terminated arrays of characters. This includes functions like strlen and strcpy. It's the C++ version of the classic string.h header from C.

The string header provides the std::string class and related functions and operators.

The headers have similar names, but they're not really related beyond that. They cover separate tasks.

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