c++将文本文件读入整数和字符串

Question

我有一个文本文件的标准读入，但我需要的是一行的前 3 个字符作为 int 读入，该行的其余部分作为字符串逐行读入。我已将示例文本放在下面的代码中。

#include <fstream>
#include <iostream>
using namespace std;

int main () 
{
 char buffer[256];
 ifstream myfile ("example.txt");

  while (! myfile.eof() )
  {
    myfile.getline (buffer,100);
    cout << buffer << endl;
  }
  return 0;
}

Answer 1

大概是这样的(伪代码，相信你能看懂真正的操作!)

std::string line;
ifstream myfile ("example.txt");

// this gets a line of text from the file.
while(std::getline(myfile, line))
{
  // now you need to extract three characters and convert to int, so is it always guranteed?
  if (line.size() > 3)
  {
    std::string int_s = <substring from 0, size: 3>; // lookup this function in a reference!
    std::string rest_s = <substring from 3 to end>; // ditto for the lookup

    // now convert the integer part.
    long int int_v = <conversion routine, hint: strtol>; // lookup syntax in reference.
    // use...
  }
}