逐行读取文件 [英] Read from a file line by line

问题描述

解决方案

如何从一个文本文件中逐行读取，然后使用相同的数组来保存它们。首先，你似乎在代码中使用 using namespace std; 。 这是非常不鼓励的。这是我将如何使用 std :: vector 。首先，您必须导入< vector> 头文件。

  std :: ifstream in_file（file.txt）; 
 if（！in_file）{...} //处理文件不存在的错误
 
 std :: vector< std :: string> vec; 
 std :: string str; 
 
 //将每行插入vec 
 while（std :: getline（in_file，str））{
 vec.push_back（str）; 
} 
  

std :: ifstream ' .close（）方法在它的析构函数中被处理，因此我们不需要包含它。这更干净，读起来更像英语，并没有神奇的常数。此外，它使用 std :: vector ，这是非常有效的。

>修改 std :: string [] 作为每个元素：

  std :: ifstream in_file（file.txt）; 
 if（！in_file）{...} //处理文件不存在的错误
 
 std :: vector< std :: string []& vec; 
 std :: string str; 
 
 //将每行插入到vec 
 while（std :: getline（in_file，str））{
 std :: string array [1]; 
 array [0] = str; 
 vec.push_back（array）; 
} 
  

How can I read from a text file line by line , then use the same array to save them ..

解决方案

Firstly, it seems that you are using using namespace std; in your code. This is highly discouraged. Here is how I would use std::vector. First, you have to import the <vector> header file.

std::ifstream in_file("file.txt");
if (!in_file) { ... } // handle the error of file not existing

std::vector<std::string> vec;
std::string str;

// insert each line into vec
while (std::getline(in_file, str)) {
    vec.push_back(str);
}

std::ifstream's .close() method is handled in its destructor, so we don't need to include it. This is cleaner, reads more like English, and there are no magical constants. Plus, it uses std::vector, which is very efficient.

Edit: modification with a std::string[] as each element:

std::ifstream in_file("file.txt");
if (!in_file) { ... } // handle the error of file not existing

std::vector<std::string[]> vec;
std::string str;

// insert each line into vec
while (std::getline(in_file, str)) {
    std::string array[1];
    array[0] = str;
    vec.push_back(array);
}

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