Thread: file copy program with arguments taken in main function

I use Linux system with GNU gcc compiler.

I have written the following code for copying string of one file to another.
-this code mainly take two file names as input and copies from one to another.
> the program is compiled and has no errors but the problem is that when I first give input in the terminal like

PHP Code:

filecopy file1.txt file2.txt 


Its saying no command exists....
the same I used in windows dos and it worked.

what kind of command should I use while giving input ?

Code:

# include <stdio.h>
# include <stdlib.h>

int main ( int argc, char *argv[] )
{
    FILE *psCopy, *psPaste ;
    char ch ;
   
    if ( argc != 3 )
      {
        printf("Insufficient number of arguments\n");
        exit (101);
      }  
    
    psCopy = fopen ( argv [1], "r" );
    if ( !psCopy )
      {
        printf ("File couldn't open. Sorry!\n");
        exit (102);
      }
    
    psPaste = fopen ( argv [2], "w" );
    if ( !psPaste )
    {
       printf ("File couldn't open. \n");
       exit (201);
    }

    while ( (fscanf (psCopy,"%c",&ch)) == 1 )
      fprintf (psPaste,"%c",ch) ;

   fclose (psCopy) ;
   fclose (psPaste) ;

return ;
}

Use the ls command or a filebrowser so you can see what does and does not exist in your current working directory. Gcc by default always creates a file called "a.out". If you want to call it something else, use "-o" to specify:

Code:

gcc -Wall mysource.c -o programname

Always use "-Wall" with gcc too. If the program cannot open the file, you should tell the user a bit more about why:

Code:

#include <errno.h>

[.....]

    if ( !psCopy )
      {
        printf ("File couldn't open: (%d) %s\n", errno, strerror(errno);
        exit (102);
      }

This may help to explain the issue.

So, it looks like your first file is not valid, you can confirm this by doing:

Code:

echo $?

after you have tried the program since you return unique numbers on each test.

Could be anything from that the file doesn't exist in the current directory to a spelling error.

Originally Posted by suryak

I'm not able to fix with them and I feel so confused.
Please tell me clearly where I'm doing wrong and what should I do.

Okay...

Assuming all my source code file and the files that I am using for copying are in the default location where generally a.out is present.

If you are assuming that, that is what you are doing wrong. Assuming things are how you think they should be will get you nowhere fast You need to make certain of what you are doing.

If you mean that I should assume that, then I will believe you. Did you try using strerror() like I suggested before? What error did you get? BTW (sorry) I forgot you need string.h and errno.h to use strerror():

Code:

#include <stdio.h>
#include <errno.h>
#include <string.h>

int main(void) {
	FILE *dud = fopen("non-existent file", "r");

	if (!dud) printf("Errno = %d\n%s\n", errno, strerror(errno));

	return 0;
}

Here's what that does for me:

Code:

[root~/C] gcc -Wall test.c -o example
[root~/C] ./example
Errno = 2
No such file or directory