Invalid Page Faults with Command Line Args

Hello. I was making a command line xor encryption tool (mainly for fun), and I did most of it pretty good. But when I compile it (without any errors or warnings), and then run it with the nessesary arguments, it throws a invalid page fault at me. :(

Well here is a snippet of the code (a bit large to post the entire thing...):

Code:

---

void fSyntax()
{
        cout << "\nThe correct syntax is: <filename> <password> [--decrypt]\n";
        exit(1);
}

int main(int argc, char *argv[])
{
        int i;
        if((argc < 2) || (argc > 3))
                fSyntax();
        while( i < argc )
        {
                if(!strcmp(argv[argc],"--decrypt"))
                {
                        fstream FileD(argv[1], ios::in | ios::out | ios::nocreate);
                        if(!FileD)
                                exit(1);
                        fDecrypt(FileD, argv[2]);
                        FileD.close();
                        exit(1);
                }
                i++;
        }
        fstream FileE(argv[1], ios::in | ios::out | ios::nocreate);
        if(!FileE)
                exit(1);
        fEncrypt(FileE, argv[2]);
        FileE.close();
        return 0;
}

---

Now what do I do? :p

I'm thinking it has something to do with the while() loop, but I can't be sure on that.

Well, thanks for your help.

if(!strcmp(argv[argc]
argv is an array that it argc elements long -- argv[0] to argv[argc-1].

argv[argc] is an out of bounds index.

>>argv[argc] is an out of bounds index.
In normal array terms it would be out of bounds, but for command line args, argv[argc] is a NULL pointer.

Aha, i fixed it.

Code:

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int i;

---

was supposed to be

Code:

---

int i = 0;

---

:p

Quote:

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Originally posted by Hammer
>>argv[argc] is an out of bounds index.
In normal array terms it would be out of bounds, but for command line args, argv[argc] is a NULL pointer.

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Good catch, I forgot that one.

Quote:

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Originally posted by KneeLess
Aha, i fixed it.

Code:

---

int i;

---

was supposed to be

Code:

---

int i = 0;

---

:p

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... which is why a for loop would have been a better choice, imo. It makes mistakes like that easier to see.