Get output to the Console window in C++ - c++

Question

so i am new to C++ and I was hoping the community could help me with my homework. Now im not asking for someone to do it for me because i am very capable of doing it on my own, i am just asking for help on a particular part. So, my assignment involved making a program that could be able to find and print all of the prime numbers between 2 and 100. I have to use a double loop (its what my professor said), so i have set up an if statement to run through all of the numbers from 2 to 100 and have a second loop inside the first one to determine if the current number is a prime number and then print it. Here is where my issue comes into play, when i run it, it opens the console window and closes it so fast i cannot see if anything did print to it. So i added a break point to see if it did. When i press F5 to step into each next step, it runs through the loop once and then it starts jumping over to different windows reading the lines of different source files (i think they are source files). Eventually the console window closes with nothing printed to it, and it doesn't start the loop over again like it should. My question is this, like in Visual Basic where you can put console.readline() so a button has to be pressed from the keyboard in order to continue, how can you do the same in C++ so that after the loop to see if the number is prime ran and printed the number, the program will wait for a key to be pressed right after it was printed?
Here is my current code as follows, Thanks again for any help, I really appreciate it.
#include "stdafx.h"
#include<iostream>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
int counter=2;
int primeCounter=counter;
//two variables, one to keep track of the number we are one, the other to check to see if its prime.
if(counter<101)
{//I want the counter to increment by 1 everytime the loops runs until it gets to 100.
if(!(counter%(primeCounter-1)==0))//if the counter has a remainer, then it is prime
{//each time the main loop run i want this loop to run too so it can check if it is a prime number and then print it.
cout<<counter<<endl;
//if this was VB, here is where i would want to have my console.Readline()
}
else
{
}
counter+=1;
}
else
{
}

Answer 1

Since you're using Visual Studio you can just use Ctrl+F5 to run your program without debugging. That way the console window stays after the program's finished.
Alternatively you can run the program from the command line.
Or you can put a breakpoint on the last } of main and run it in a debugger.
It's not a good idea to add a “stop here” at the end.
If you want see each line of output as it's produced, just place a breakpoint after the output statement and run the program in the debugger, in Visual Studio keypress F5.
In passing, <stdafx.h> is not a standard header. It's in support of Visual C++ precompiled headers, which is a feature that yields quite non-standard preprocessor behavior. Better turn that off in the project settings, and remove the >stdafx.h> include.
Also
int _tmain(int argc, _TCHAR* argv[])
is a silly non-standard Microsoft-ism, at one time in support of Windows 9x, but no longer with any purpose other than vendor lock-in.
Just write standard
int main()
or with trailing return type syntax,
auto main() -> int
Finally, instead of
!(counter%(primeCounter-1)==0)
just write
counter%(primeCounter-1) != 0

Answer 2

cin.get() will do what you want.

Answer 3

In Visual Studio you can actually call system("pause"); in a place you need to suspend your app.

Answer 4

so i figured out my issue. First off the loop wasnt running because the first if statement didnt loop. I changes this to a while and now the output works like a charm. take a look
#include "stdafx.h"
#include<iostream>
using namespace std;
int main()
{
int counter=2;
int primeCounter=counter;
//two variables, one to keep track of the number we are one, the other to check to see if its prime.
while(counter<101)
{//I want the counter to increment by 1 everytime the loops runs until it gets to 100.
if((counter%(primeCounter-1)==0))//if the counter has a remainer, then it is prime
{//each time the main loop run i want this loop to run too so it can check if it is a prime number and then print it.
}
else
{
cout<<counter<<endl;
}
counter+=1;
primeCounter=counter;
}
}
now i just need to polish the condition to actually figure out the prime numbers. thanks again for your help.!!!!