Inputting data in command line.

[mariusz]

Hi

I want to create a program that would read data from file data1.dat and would be run by typing this into the command line:

$ program.tsk data1.dat

how would I go about doing this?
I appreciate your help!

[whiteflags]

Cprogramming.com Tutorial: Command-Line Arguments

[WaltP]

Do you know anything at all about C and File I/O?

[mimatech ug]

When executing a program on command line, you start with the program name, a space and then whatever arguments you like.

C:\ myprogram.exe "file.dat"

So your program will take "file.dat" as a string argument and you can process it as required.

[CommonTater]

When executing a program on command line, you start with the program name, a space and then whatever arguments you like.

C:\ myprogram.exe "file.dat"

So your program will take "file.dat" as a string argument and you can process it as required.

You don't need the quotes and the space after the drive letter will cause that to fail...
Like this .... c:\myprogram file.dat

On Windows the only time you need quotes around a filename is when it has spaces in it...
as in c:\myprogram "c:\my documents\file.dat"

[Babkockdood]

#include <stdio.h>

int main(int argc, char *argv[]) {
    if (!argv[1]) {
        printf("USAGE: %s filename\n", argv[0]);
        return 1;
    }
    FILE *fp = fopen(argv[1], "r");
    /* more code here... */
    return 0;
}

argv[0] is the string entered into the command prompt to start the program. So if you type prog.exe into the prompt (assuming this compiled program's name is prog.exe), you will see the usage message. argv[1] is the first command-line argument. So if you type prog.exe file.txt into the prompt, the program will open file.txt for reading, and then you can use fscanf and such.

argc tells how many command-line arguments were entered. argv[] is an array of strings, each containing a command-line argument. Hope this helps.