我可以使用！=和C ++ ==为字符串比较不写我自己？ [英] Can I use != and == in C++ for string comparison without writing my own?

问题描述

有什么在换句话说字符串比较C和C ++之间的区别？

我是从'C'阵营。我看到程序中使用==比较字符串，我试图找到它的过载程序，但是没有找到。这是否意味着C ++处理字符串（的char []）自然地==和！=？结果
如果我有我自己定义的String类，这将是相同的，我可以使用==和！=没有定义呢？或者它仅适用于的char []？搜索结果
编辑：结果
它看起来像我C混合的的char []与C ++ std :: string类。 OK，这个老问题仍然适用。一些随后的问题如下：结果
我的程序定义的char []变量，但与==操作符进行比较。这似乎工作。他们是C风格的字符串，但一起工作==。难道编译器自动将其转换为为std :: string对我来说，这样的程序工作？_爱
EDIT2：结果
这里是一个工作的样本。结果

 如果（名称==）的回报;
 

，其中名是一类MyString的项目。它有一个参数的char *一个construtor。结果
MyString的具有公共职能的数据（），它返回的char * C风格的字符串指针。结果
所以，我是比较MyString的对象？或C风格的字符串？结果
无过载！=我自己，我可以做类似下面？

 如果（name.data（）！= somes_ [I]。数据（））
....
 

解决方案

的这是否意味着C ++处理字符串（的char [] ）使用<$自然C $ C> == 和！= ？的

否即可。这是不对的<$比较相互之间的C风格的字符串（即的char [] 或的char * ） C $ C> == 或！= （以C和C ++），因为你最终会比较指针，而不是字符串。

在C ++中，可以比较 STD ::字符串 与C风格的字符串或其它的 的std ::字符串 因为的std ::字符串的对象的 运算符== 和 运算符！= ：

 的std ::字符串STR1（ABC），STR2（DEF）;
如果（STR1 = STR2＆安培;！＆安培; STR1 ==ABC）
    性病::法院LT＆;＆LT; 是的，我知道了。
 

What's difference between C and C++ in string comparison in other words?

I came from 'C' camp. I saw program using == to compare strings, I tried to find its overloading program, but did not find one. Does it mean C++ deal with string (char []) naturally with == and !=?
If I have my own defined String class, would it be same that I can use == and != without defining them? or it applies only to char []?

Edit:
It looks like I mixed C's char[] with C++ std::string class. OK, the old question still apply. Some followed questions as below:
My programs defined char[] variables, but compared with "==" operator. It seemed work. They are C-style string, but work with "==". Did compiler auto-convert them to std::string for me so that the programs worked?

Edit2:
Here is a working sample.

if(name == "") return;

where "name" is a MyString class item. It has a construtor with a parameter char*.
MyString has a public function data(), it returns char* C-style string pointer.
So, am I comparing MyString objects? or C-style strings?
Without overload "!=" myself, can I do something like below?

if( name.data() != somes_[i].data() )
....

解决方案

"Does it mean C++ deal with string (char []) naturally with == and !=?"

No. It is wrong to compare C-style strings (i.e. char[] or char*) between each other with == or != (in both C and C++), because you will end up comparing pointers rather than strings.

In C++ it is possible to compare std::string object with a C-style string or another std::string object because of the std::string's operator== and operator!=:

std::string str1("abc"), str2("def");
if (str1 != str2 && str1 == "abc")
    std::cout << "Yep, I got it.";

这篇关于我可以使用！=和C ++ ==为字符串比较不写我自己？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！