C ++ int to string，连接字符串 [英] C++ int to string, concatenate strings

问题描述

我是C ++的新手，正在开发一个简单的项目。基本上我遇到一个问题是在文件名中创建一个带有一个数字（int）的文件。正如我看到的，我必须首先将int转换为字符串（或char数组），然后将这个新的字符串与文件名的其余部分连接。

在这里是我的代码到目前为止无法编译：

  int n; // int to include in filename 
 char buffer [33]; 
 itoa（n，buffer，10）; 
 string nStr = string（buffer）; 
 
 ofstream resultsFile; 
 resultsFile.open（string（File  - ）+ nStr + string（。txt））; 
  

这会产生几个编译错误（在Linux中编译）：

1. itoa未在此范围内声明


2. 没有匹配的函数调用'std :: basic_ofstream char，std :: char_traits char :: open（std :: basic_string char，std :: char_traits char，std :: allocator char）'

此处： c字符串和int连接
，此处为：最简单的方法将C ++中的int转换为字符串，没有运气。 / p>

如果我使用to_string方法，我最终得到错误to_string不是std的成员。

解决方案

您可以使用 stringstream p>

  std :: ostringstream filename; 
 filename<< File  - << n<< 。文本; 
 resultsFile.open（filename.str（）。c_str（））; 
  

I'm new to C++ and working on a simple project. Basically where I'm encountering a problem is creating a file with a number (int) in the file name. As I see it,I have to first convert the int to a string (or char array) and then concatenate this new string with the rest of the file name.

Here is my code so far that fails to compile:

int n; //int to include in filename
char buffer [33];
itoa(n, buffer, 10);
string nStr = string(buffer);

ofstream resultsFile;
resultsFile.open(string("File - ") + nStr + string(".txt"));

This gives a couple compilation errors (compiling in Linux):

1. itoa not declared in this scope
2. no matching function for call to ‘std::basic_ofstream char, std::char_traits char ::open(std::basic_string char, std::char_traits char , std::allocator char )’

I've tried the advice here: c string and int concatenation and here: Easiest way to convert int to string in C++ with no luck.

If I using the to_string method, I end up with the error "to_string not a member of std".

解决方案

You could use a stringstream to construct the filename.

std::ostringstream filename;
filename << "File - " << n << ".txt";
resultsFile.open(filename.str().c_str());

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