性病的每个字符地址::字符串 [英] Address of each character of std::string

问题描述

我试图打印性病的每个字符:: string的的地址。但我呆在一起理解什么与内部发生的std ::字符串而对于数组这是给的地址如我所料是造成此输出。可能有人请解释一下到底是怎么回事？

 的#include＆LT;＆iostream的GT;
＃包括LT＆;串GT;使用命名空间std;诠释主（）{   字符串str =你好;
   诠释一个[] = {1,2,3,4,5};   的for（int i = 0; I＆LT; str.length（）; ++ I）
      COUT＆LT;＆LT; ＆放大器;海峡[1]  - ;＆下; ENDL;   COUT＆LT;＆LT; **************＆LT;＆LT; ENDL;   对（INT I = 0; I＆小于5 ++ⅰ）
      COUT＆LT;＆LT; ＆放大器;一[1]  - ;＆下; ENDL;    返回0;
}
 

输出：

 你好
ELLO
LLO
罗
Ø
**************
0x7fff5fbff950
0x7fff5fbff954
0x7fff5fbff958
0x7fff5fbff95c
0x7fff5fbff960
 

解决方案

在的std :: ostream的试图打印的char * 它假定它是一个C风格的字符串。

其转换为无效* 打印前，你会得到你所期望的：

  COUT＆LT;＆LT; （无效*）及海峡[1]  - ;＆下; ENDL;
 

I tried to print the address of each character of std::string. But I amn't understanding what is happening internally with std::string that is resulting this output while for the array it is giving the address as I expected. Could someone please explain what is going on?

#include <iostream>
#include <string>

using namespace std;

int main(){

   string str = "Hello";
   int a[] = {1,2,3,4,5};

   for( int i=0; i<str.length(); ++i )
      cout << &str[i] << endl;

   cout << "**************" << endl;

   for( int i=0; i<5; ++i )
      cout << &a[i] << endl;

    return 0;
}

Output:

Hello
ello
llo
lo
o
**************
0x7fff5fbff950
0x7fff5fbff954
0x7fff5fbff958
0x7fff5fbff95c
0x7fff5fbff960

解决方案

When a std::ostream tries to print a char* it assumes it's a C-style string.

Cast it to a void* before printing and you will get what you expect:

cout << (void*) &str[i] << endl;

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