异常处理和打开文件?

Is it possible to use exceptions with file opening as an alternative to using .is_open()?

是否可以使用带有文件打开的异常作为使用.is_open()的替代方法?

For example:

例如:

ifstream input;

try{
  input.open("somefile.txt");
}catch(someException){
  //Catch exception here
}

If so, what type is someException?

如果是，什么类型是例外?

3 个解决方案

#1

http://en.cppreference.com/w/cpp/io/basic_ios/exceptions

Also read this answer 11085151 which references this article

也请阅读参考本文的答案11085151

// ios::exceptions
#include <iostream>
#include <fstream>
using namespace std;

void do_something_with(char ch) {} // Process the character 

int main () {
  ifstream file;
  file.exceptions ( ifstream::badbit ); // No need to check failbit
  try {
    file.open ("test.txt");
    char ch;
    while (file.get(ch)) do_something_with(ch);
    // for line-oriented input use file.getline(s)
  }
  catch (const ifstream::failure& e) {
    cout << "Exception opening/reading file";
  }

  file.close();

  return 0;
}

Sample code running on Wandbox

在Wandbox上运行的示例代码

EDIT: catch exceptions by const reference 2145147

编辑:通过const引用2145147捕获异常

EDIT: removed failbit from the exception set. Added URLs to better answers.

编辑:从异常集中删除故障位。添加url以获得更好的答案。

#2

From the cppreference.com article on std::ios::exceptions

关于std: ios::例外。

On failure, the failbit flag is set (which can be checked with member fail), and depending on the value set with exceptions an exception may be thrown.

在失败时，设置failbit标志(可以与member fail一起检查)，并根据带有异常的值设置抛出异常。

#3

I think while (!file.eof()) statement should not be in the try scope..

我认为while (!file.eof()语句不应该在try范围内。

#1