Thread: Add not overwrite to a file

  1. #1
    Registered User
    Join Date
    Oct 2002
    Posts
    22

    Add not overwrite to a file

    I have to write a program that emulates the Unix cat command. The program accepts between 2 to 9 files from dos command line.
    eg concat file 1 file 2 file3 ...... // concat being the name of my program....files 2 and 3 will be copied to file 1 in that order.....I can't seem to get my program to add file 2 and 3 to file 1....it always overwrites file 1....this is the code I have...





    Code:
    int main(int argc, char* argv[])
    {
    	if((argc < 2 ) || (argc > 9))
    	{
    		cerr << "\nFormat: ocopy srcfile destfile";
    		exit(1);
    	}
    
    	char ch;
    
            ofstream outfile;		//create output file
            outfile.open(argv[1]);	//open output file
    
    
    	if(!outfile)
    	{cerr << "\nCan't open " << argv[1]; exit(1);}
    
            for (int i = 1; i < argc; i++)
    	{
                    ifstream infile;		//create input file
    	        infile.open(argv[i]);	        //open file
    
    
    	        if(!infile)
    	        {cerr << "\nCan't open " << argv[i]; exit(1);}
    
            	while(infile)			//until EOF
    	        {
    		        infile.get(ch);		//read a character
    		        outfile.put(ch);	//write a character
    	        }
            }
    	return 0;
    }
    Any suggestions would be great...thanks...

  2. #2
    Amateur
    Join Date
    Sep 2003
    Posts
    228
    Why not just use the append opening mode?

  3. #3
    Registered User
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    Oct 2002
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    Not sure how to use append???

  4. #4
    Registered User
    Join Date
    Oct 2001
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    2,934
    Try closing infile after reading each file.
    Code:
            for (int i = 1; i < argc; i++)
    	{
                    ifstream infile;		//create input file
    	        infile.open(argv[i]);	        //open file
    
    
    	        if(!infile)
    	        {cerr << "\nCan't open " << argv[i]; exit(1);}
    
            	while(infile.get(ch))			//read until EOF
    	        {
    		        outfile.put(ch);	//write a character
    	        }
    		infile.close();
            }
    Last edited by swoopy; 10-02-2003 at 12:37 PM.

  5. #5
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    thanks...but that doesn't work.....

  6. #6
    Amateur
    Join Date
    Sep 2003
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    228
    On how to use append, take a look at your library's references.

  7. #7
    End Of Line Hammer's Avatar
    Join Date
    Apr 2002
    Posts
    6,231
    Originally posted by Bones
    Not sure how to use append???
    Hint
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  8. #8
    Registered User
    Join Date
    Oct 2002
    Posts
    22

    Cheers

    Thanks ....I managed to get my program working with append....

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