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How to pass parameters to main() and use them?

 
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How to pass parameters to main() and use them?
crammer008
post 28 Mar, 2006 - 02:38 AM
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Dear all,

I have the following code:

CODE

int main(int argc, char *argv[])
{
   int i;
   for (i=0;i<=argc;i++)
   {
     cout<<"argv["<<i<<"]: "<<argv[i]<<endl;
   
   }
 return 0;
}


Assume the code is compiled to be "openfile.exe".
If I type "openfile data.txt" in DOS mode, obviously the string "data.txt" will be passed to main() function.
My question is: How to save the content of the argv[1] to a string variable? Although I can use "cout" to display the content of argv[] on screen I don't know how to transfer its content to another variable because I want to use the content to do some operation in main() function.

Looking forward to your guidance!
Thanks a lot!
Crammer008

This post has been edited by Dark_Nexus: 29 Mar, 2006 - 09:19 AM
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sontek
post 28 Mar, 2006 - 02:48 AM
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I'm not that familiar with C++ but I think you could do something like

CODE

ofstream stream;
stream.open (argv[i]);
stream >> stringVariable
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crammer008
post 28 Mar, 2006 - 02:53 AM
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The problem is I have to type the command line like the below:

CODE

openfile mytxt


So I have to do the following operation in main() function:

CODE

"mytxt"+".txt" = mytxt.txt


So using string variable to operate it is necessary.
How to do it?

Thanks a lot!
Crammer008

This post has been edited by Dark_Nexus: 29 Mar, 2006 - 09:20 AM
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Amadeus
post 28 Mar, 2006 - 06:50 AM
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g++ -o drink whiskey.cpp

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Do you need an actual string object, or a c style string of characters?
CODE

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

int main(int argc, char *argv[])
{
  string arg1 = argv[1];
  //char *arg1 = argv[1];
  cout<<arg1<<endl;
  return 0;
}

Uncomment the char line and comment the string line, depending on what suits your needs.

Alternately, you can declare a vector of strings, and push each argument onto the pile, then pop as required.
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crammer008
post 28 Mar, 2006 - 08:41 AM
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thank you very much:)

Your code give me great help:)

Crammer008
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