C ++检查命令行参数

Question

I need to check for two separate file names in a command line argument.

./a.out hello.txt hello2.txt

The following code is not producing an error when the two file names are identical.

  #include <stdio.h>
  #include <iostream>
  #include <stdexcept>

  using namespace std;

  int main (int argc, char *argv[])
  {
     try
     {
        if (argc != 3 || argv[1] == argv[2])
        {
           throw invalid_argument("Error");
        }
     }
     catch (invalid_argument &ex)
     {
        cout << ex.what() << '\n';
     }
  }

Answer 1

argv is a string so you cannot compare "==" operator. You use strcmp in string.h

if (argc != 3 || strcmp(argv[1],argv[2])==0)
    {
       throw invalid_argument("Error");
    }

Answer 2

This line

argv[1] == argv[2]

compares pointers, not the actual string values

Try

!strcmp(argv[1] , argv[2])