简单的c ++文件打开问题

Question

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

int main ()
{
  ofstream testfile;
  testfile.open ("test.txt");
  testfile << "success!\n";
  testfile.close();
  return 0;
}

1)调用"g ++ testfile.cpp"
2)创建"test.txt"
3)调用"chmod u + x a.out"
4)???
5)文件保持空白.

我觉得自己是一个傻瓜,因为这应该是一件微不足道的事情.

Answer 1

执行文件I/O时,您几乎总是需要测试错误:

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

int main ()
{
  ofstream testfile;
  testfile.open ("test.txt");
  if ( ! testfile.is_open() ) {
     cerr << "file open failed\n";
     return 1;
  }

  if ( ! testfile << "success!\n" ) {
     cerr << "write failed\b";
     return 1;
  }

  testfile.close();   // failure unlikely!
  return 0;
}