Why is this.

[Help]

Can someone tell me what this means.
I see it in alot of programs.
The part I am confused on is the
if((argc<2) || (argc>3))
{ proceed w. code

Why do they put that at the beginning of code ?


#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
void main(int argc, char *argv[])


{
unsigned char car, dump;
FILE *in, *out;
long int i, perc, cont;
i=1;
perc=1;
cont=0;
if ((argc<2) || (argc>3))


{


Thanks

[parksie]

It means that argc must be either 2 or 3.

|| == Logical OR

A high level answer is that they are testing to see if 2 and only 2 parameters were passed in on the command line to start the app.

app arg1 arg2

as opposed to:
app
app arg1
app arg1 arg2 arg3
app arg1 arg2 arg3 argN etc.

[parksie]

It's >3 so 3 is acceptable... ;)

[Help]

See I understand all of that,
What I dont understand is what arguments are passed at the beginning.,

I never knew arguments where passed right when the main function is hit.

The user has no controll over those arguments , so what is the point of them.

[parksie]

Ah...but the user does :)

argv[0] is always the location of the program. The rest of the array up to index (argc-1) are the arguments passed on the command line:

myprog arg1 arg2

argv[0] = "c:\programs\myprog.exe"
argv[1] = "arg1"
argv[2] = "arg2"

argc = 3

Yeah, I miscounted. They want either:
app arg1
or
app arg1 arg2

Is that right parksie?

Help
The user has no controll over those arguments , so what is the point of them.

The user enters either "arg1" or "arg1 arg2" when launching "app".