C - read/write form a file having a dynamic name

Question

I want to make a C program which will be called with some parameters; Each parameter will represent a filename and I want to write some stuffs in each of them.

FILE * h0;    
h0 = fopen(argv[0],"w");    
char buffer[100] = "something here\n";    
fprintf(h0,buffer);    
fclose(h0);

For C++ there is something called c_str() but I didn't manage to use it here. Any tips how to handle it?

possible duplicate of [C - reading command line parameters](http://stackoverflow.com/questions/5157337/c-reading-command-line-parameters) — Mahmoud Al-Qudsi, May 06 '12 at 07:49
(Fixed your formatting: the correct way to format code is to indent it 4 spaces, you can do this by selecting your code and pressing the button labelled `{}`) — huon, May 06 '12 at 07:50
so what is the problem? add some error checking code and are you not good to go? — ConfusedAboutCPP, May 06 '12 at 07:50

score 1 · Accepted Answer · answered May 06 '12 at 07:56

A file name is exactly a C string (null terminated array of char) and you've already answered your own question (you don't need anything like c_str in C), since you open the file and you write in it. The argc tells you how many arguments there are in the command line, the name of the program inclusive and it is at argv[0]. So you need a loop, like

const char *your_stuff = "something here\n";
for(i = 1; i < argc; i++)
{
   FILE *h = fopen(argv[i], "w");
   if (h) {
     fputs(your_stuff, h);
     fclose(h);
   }
}

or something like that.

so, the problem was that i tried to write to argv[0]; thanks a lot - problem solved — 55651909-089b-4e04-9408-47c5bf, May 06 '12 at 08:06

score 1 · Answer 2 · answered May 06 '12 at 07:56

1

You should look at how the command line arguments are formed:

http://crasseux.com/books/ctutorial/argc-and-argv.html

Then have a look at your argv[0].

answered May 06 '12 at 07:56

Ben Ruijl

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C - read/write form a file having a dynamic name

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