Quick Loop Question

How would I go about looping this?

Code:

---

    cout << "Please enter the number of prompts you desire: ";
    getline (cin, NumPrompts); "\n";
   
   

      std::string command("C:\\windows\\system32\\ping.exe ");
      command.append(" ").append(Address);
      command.append(" ").append(Parameter);
      command.append(" ").append(Bytes);
      system(command.c_str());

---

I know about the for loop, about the while loop etc. But my interest is in doing a loop with a variable. Like, you enter 5 for NumPrompts and it makes 5 prompts. Or you enter 10 and it makes 10, etc. Before you redirect me to MSDN, or elsewhere: Please know I already looked. I would greatly appreciate any help.

-Nightwarrior

Edit: Oh yeah, whenever I try to use for or while, my compiler (dev c++) gives me an error that command is undeclared, but it runs fine without the loop.

You can't loop though a bunch of named variables. That's what arrays are for. :) With an array, it's easy.

[edit]

Code:

---

for(int x = 0; x < 3; x ++) {
    command.append(" ").append(array[x]);
}

---

[/edit]

[edit=2] I think that I've misunderstood what you're trying to do. Are you just trying to do this?

Code:

---

for(int x = 0; x < NumPrompts; x ++) {
    system(command.c_str());
}

---

BTW, this "\n" does nothing:

Code:

---

getline (cin, NumPrompts); "\n";

---

I think you put the ) in the wrong place.
[/edit]

Do you need something like this?

Code:

---

    int NumPrompts;
    cout << "Please enter the number of prompts you desire: ";
    cin >> NumPrompts;

    int i=0;
    while (i++ < NumPrompts)
    {
        std::string command("C:\\windows\\system32\\ping.exe ");
        command.append(" ").append(Address);
        command.append(" ").append(Parameter);
        command.append(" ").append(Bytes);
        system(command.c_str());
    }

---

My second edit does that in a much more efficient way, noodles.

Code:

---

for(int i=NumPrompts;i;--i)

---

Eh. The standard idiom is to loop from 0 to NumPrompts-1 inclusive, or [0,NumPrompts). That's just backwards. :)

Besides, if you're doing it that way, you don't even need a loop variable.

Code:

---

do {
    // code
} while(--NumPrompts);

---

...

You need to declare the array. Something like this, perhaps.

Code:

---

std::string parameter[3];
parameter[0] = "one";  // whatever was in the variable Address
parameter[1] = "two";  // whatever was in Parameter
parameter[2] = "three";  // whatever was in Bytes

std::string command("C:\\windows\\system32\\ping.exe ");
for(int x = 0; x < 3; x ++) {
    command.append(" ").append(parameter[x]);
}
std::system(command.c_str());

---

Alright, I'll mess around with that a little. My goal is though, to start as many ping.exe's as the NumPrompts variable.

Here's the full code (might help explain it more):

Code:

---

#include <cstdlib>
#include <iostream>
#include <windows.h>

using namespace std;

int main()
{
    string Address;
    string Parameter;
    string Bytes;
    int NumPrompts;
   
    cout << "Please Enter The I.P. Address: ";
    getline (cin, Address); "\n";
    cout << "Please Enter any Parameters you wish to include (example: -t -l): ";
    getline (cin, Parameter); "\n";
    cout << "Please enter the byte number you wish to send (-l # (# = 0-65500)): ";
    getline (cin, Bytes); "\n";
    cout << "Please enter the number of prompts you desire: ";
    cin >> NumPrompts; "\n";
   
   

        std::string command("C:\\windows\\system32\\ping.exe ");
        command.append(" ").append(Address);
        command.append(" ").append(Parameter);
        command.append(" ").append(Bytes);
        system(command.c_str());


     

    system("PAUSE");
    return EXIT_SUCCESS;
}

---

Code:

---

  int i=0;
    while (i++ < NumPrompts)

---

Why not use a for-loop - that's what they are for (pun intended :) ).

--
Mats

None of the loops are actually starting more than 1 command prompt w/ ping in it. They all only start one. :(

Well, system() is defined to start a new task/process, and wait for it to finish. So by definition, you'll get four (for example) pings running one after another - not in parallel.

If you want to run multiple instances, then you need to use something other than system - perhaps spawn(), CreateProcess(), ShellExecute() or some other similar function.

I doubt that your loop in itself is wrong - and if you want to count from one number to another, a for-loop is really the most obvious and natural mechanism to use.

--
Mats

Quote:

---

Originally Posted by matsp

Well, system() is defined to start a new task/process, and wait for it to finish. So by definition, you'll get four (for example) pings running one after another - not in parallel.

If you want to run multiple instances, then you need to use something other than system - perhaps spawn(), CreateProcess(), ShellExecute() or some other similar function.

I doubt that your loop in itself is wrong - and if you want to count from one number to another, a for-loop is really the most obvious and natural mechanism to use.

--
Mats

---

Thanks for the reply. I was using ShellExecute before, but I couldn't get it to work; so I swapped over to this (since this is the help someone else offered me). I have no idea how to go about all of this in c++, due to being a newb. Maybe I should just stick to VB. =/

A simple way to do it is to use the program start, which is Windows-specific, but then so is ShellExecute(). Just use

Code:

---

std::string command("start C:\\windows\\system32\\ping.exe ");
// ...

---

and you'll get the ping in a new window. You may have to wrap double quotes around your command, I can't remember exactly how start works, and this is a Linux system.

The XP version of start has some interesting features. For example, you can start a program minimized or maximized.

Quote:

---

Originally Posted by dwks

A simple way to do it is to use the program start, which is Windows-specific, but then so is ShellExecute(). Just use

Code:

---

std::string command("start C:\\windows\\system32\\ping.exe ");
// ...

---

and you'll get the ping in a new window. You may have to wrap double quotes around your command, I can't remember exactly how start works, and this is a Linux system.

The XP version of start has some interesting features. For example, you can start a program minimized or maximized.

---

That works, thank you very much! And much thanks to the other people as well! I really learned a lot from this thread / little program. I will try to study up on how to use ShellExecute(), as well.

Again thanks and best regards,

Nightwarrior.

Edit: I forgot to mention, just adding start works, no need for double quotation marks.

Food for thought: http://faq.cprogramming.com/cgi-bin/...&id=1043284392

[edit] I hope you never have to stick to VB. :) [/edit]