Question

我想将文本文件中的内容复制到string或*char。如果我可以将文件内容复制到array个字符串（每行都是array的元素），那会更好。这是我的代码：

int main() {
   ifstream inFile;
   inFile.open("index.in.txt"); //index.in has in each line a name and at the end there is a "."
   char ab[11];
   int q=0;
   char *a[111];
   if (inFile.is_open()) {
      while (!inFile.eof()) {
         inFile >> ab; //i think i don't understand this line correctly
         a[q]=ab;
         cout<<a[q]<<endl;
         q++;
      }
   }
   else{ 
     cout<<"couldnt read file";
   }
   inFile.close();
   cout<<"\n"<<ab<<endl; //it shoud be "." and it is
   cout<<"\n"<<a[0]<<endl; //it should be "ion" but it gives me "."
   return 0;
}

a array中的所有值都等于最后一行（点

）

Answer 1

int main() {
   ifstream inFile;
   inFile.open("index.in.txt"); //index.in has in each line a name and at the end there is a "."
   std::vector< std::string > lines;
   std::string line;
   if (inFile.is_open()) {
      while ( getline( inFile, line ) ) {
         lines.push_back( line );
      }
   }
...

现在lines是一个字符串向量，每个都是文件中的一行

Answer 2

您每次都会在inFile >> ab;覆盖您唯一的缓冲区你在缓冲区中读取一行并在某处保存缓冲区的地址。下次读取同一缓冲区中的下一行并保存与第二行完全相同的地址时。如果您回读第一行，您将最终读取更新的缓冲区，即最后一行。

您可以将代码更改为

#include <vector>
#include <string>
#include <fstream>

using namespace std;
int main() {
   ifstream inFile;
   inFile.open("index.in.txt"); //index.in has in each line a name and at the end there is a "."
   string ab; //char ab[11];
   int q=0;
   vector< string > a(111); //char *a[111];
   if (inFile.is_open()) {
      while (!inFile.eof()) {
         inFile >> ab;
         a[q]=ab;
         cout<<a[q]<<endl;
         q++;
      }
    }
    else cout<<"couldnt read file";
    inFile.close();
    cout<<"\n"<<ab<<endl; //it shoud be "." and it is
    cout<<"\n"<<a[0]<<endl; //it should be "ion" but it gives me "."
    return 0;
}

最好使用std :: string和std :: vector而不是数组。

Answer 3

#include <iostream>
#include <fstream>
#include <vector>
#include <string>

bool ReadFile(const std::string &sFileName, 
              std::vector<std::string> &vLines)
{
    std::ifstream ifs(sFileName);
    if (!ifs)
        return false;
    std::string sLine;
    while (std::getline(ifs, sLine))
        vLines.push_back(sLine);
    return !ifs.bad();
}

int main() 
{
    const std::string sFileName("Test.dat");
    std::vector<std::string> vData;
    if (ReadFile(sFileName, vData))
        for (std::string &s : vData)
            std::cout << s << std::endl;
    return 0;
}

Answer 4

为了阅读一行，你必须使用std::getline。 >>运算符只会读取单词，即以空格结尾的字符序列。

请参阅：http://en.cppreference.com/w/cpp/string/basic_string/getline

将文件内容复制到字符串

4 个答案: