Visual C++ - Runtime Check Failure #3 - Variable is not initiliazed

Question

I use Visual C++ 2010 Express Edition to compile and run the .exe files I write in the C++ programming language. I am trying to create a loop-based logic using C++ to ask the user how many entries he chooses to enter, and ask questions limited to that no. of entries. For example I want to output, "How many characters do you wish to enter?: " Say the user gives the answer as '3' which is stored in the int variable 'entries'. I then want to keep asking the question 3 times before it stops and continues with the next line of code. I hope you understand, here is a block of code to demonstrate what I am doing:

#include <iostream>
#include <string>
using namespace std;

int main()
{
   cout << "How many values do you need to enter?: ";
   int entries;
   cin >> entries;
   int offset, number;
   string valueName[50];
   float valueValue[50];
   for (offset = 0; offset < entries; offset++)
   {
      cout << "Enter " << number << " Value Name: ";
      cin >> valueName[offset];
      cout << "Enter " << valueName[offset] << "\'s value: ";
      cin >> valueValue[offset];
      for (number = 1; number <= entries; number++)
      {
      }
   }
   char response;
   cin >> response;
   return 0;
}

Strangely when I run this simple program, it fails when I enter the value's name to be inserted into the 0th element of the valueName[] array. It just pauses the execution of the program and a dialog box pops up saying "Runtime Check Failure #3 - Variable 'number' is being used without being initialized!" Another problem regarding this program is that, for quite some time, when I ran this program this "Runtime Check Failure #3" box never appeared, and when it didn't, the number value went wrong, and first started with 1, and then for the next loop jumped to 6, and then repeated 6 again for the next loop!
Please help me! I've checked online scouring this problem everywhere, but it just doesn't apply to my type of problem!
Is it because the variables are out of scope?
But they're declared outside the for loops right?

So please help me!

Solution 1

The runtime is telling you the truth, the following line comes after you have declared number as an int but have not given it a value.

 cout << "Enter " << number << " Value Name: ";

In your code you declare the following, in C++ this means give me 2 ints but the values are not defined yet, e.g.

int offset, number;

Change it to something like this ..

int offset = 0;
int number = 0;

Solution 2

You are printing the variable number without assigning to it first, i.e. it's uninitialized. When it prints some random number it's because that what happens to be in the memory at the time you run the program. Assign a value to it before you use it.

Solution 3

The problem is exactly the error message you're getting. You're using the variable number without initializing it.

You use the variable right here, at the top of your loop, when it hasn't been initialized to anything yet:

cout << "Enter " << number << " Value Name: ";

What is your intention with the number variable? It doesn't really seem to be serving any purpose. If you want to print which entry you're currently on, you could use the offset variable instead, like this:

cout << "Enter " << offset << " Value Name: ";

But that still seems a little unclear to me.

But the reason that you're having a problem is because the value is uninitialized, so you're experiencing undefined behavior. This is also the reason that Visual Studio doesn't always catch it; it will probably always catch in Debug mode, but in Release mode it will almost never catch it. You need to initialize all your variables before you use them.

Comments

[Mahesh]

If anything is out of scope, compiler isn't happy. If you get run-time errors, meaning you passed the compilation phase. Syntactically everything is correct.

[Michael Burr]

If you break into the debugger when you get that message, it lands you right on the line using the uninitialized variable. Also, the build should be giving you a warning: warning C4700: uninitialized local variable 'number' used All of this tells you exactly what and where the problem is.

[Ram Sidharth]

thanks a lot Mahesh and Michael Burr for your insights, I'm happy to tell you guys that the problem has been resolved thanks to yours and everyone else's cooperation. Thank you very much.

[Ram Sidharth]

Thanks a lot for your cooperation 'eggbox'. I'm happy to tell you the problem has been resolved thanks to yours and everyone else's comments!

[Ram Sidharth]

Thank you 'Robert Kelly' for your cooperation in this problem I have been having for some time now. I'm happy to tell that the problem has been successfully resolved thanks to yours and everyone else's comments. Thank you.

[Ram Sidharth]

What you're saying is right, and thanks to your comment and many others, I have been able to resolve my problem. Thank you very much Joachim Pileborg.