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Visual Studio Confusion

RUNNER PRO AGARIO (275)
I coded a calculator that could solve normal expressions, (3+5, 6/7), and then I added a feature that could factor quadratic trinomials (ax^2+bx+c, this is unfinished as you can see in my code). The primary thing that I am wondering though is actually not related to my code, (unless you prove it to be).

Problem: So when I tested my program before initially, it worked fine. After running it again, I seem to be getting a form of assertion failure, which you can see in the error I get. Is there any way to fix this?:
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Program: ...o 2015\Projects\CalculatorRevised\Debug\CalculatorRevised.exe
File: minkernel\crts\ucrt\src\appcrt\convert\isctype.cpp
Line: 42

Expression: c >= -1 && c <= 255

For information on how your program can cause an assertion
failure, see the Visual C++ documentation on asserts.

I am wondering, what is going on, because the program worked at first, but now its not. I can't even ignore the failure, so my program just fails...

Here is my Program Code. (Please do not post anything related to sloppy algorithms or anything, I just want an answer to the Problem)
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  #include <iostream>
#include <string>
#include <cstdlib>
#include <cmath>

void run();

int main()
{
	run();
	std::cout << "\n\n";
	std::cin.get();
	return EXIT_SUCCESS;
}


void run()
{
	std::cout << "\nWelcome to Calc v1.0.\n\n";
	std::cout << "Menu:\n\n1. Basic Math (Eg: 6 + 5  or 65 / 77 or 6^3)\n";
	std::cout << "2. Trinomial Factoring (Eg: 6x^2 + 5x + 6 or 1x^2 - 6x + 3)\n";
	std::cout << "> ";
	int choice;
	std::cin >> choice;
	if (choice == 1)
	{
		while (true)
		{
			double a, b;
			char oper;
			std::cout << ">";
			std::cin >> a >> oper >> b;
			if (oper == '+')
			{
				std::cout << (a + b) << "\n";
				continue;
			}
			else if (oper == '-')
			{
				std::cout << (a - b) << "\n";
				continue;
			}
			else if (oper == '*')
			{
				std::cout << (a * b) << "\n";
				continue;
			}
			else if (oper == '/')
			{
				if (b == 0) {
					std::cout << "Error: No division by 0 permitted!\n";
					continue;
				}
				else
				{
					std::cout << (a / b) << "\n";
					continue;
				}
			}
			else if (oper == '^')
			{
				if (b == 0)
				{
					std::cout << "1\n";
				}
				else if (a == 0)
				{
					std::cout << "0\n";
				}
				else if (b < 0)
				{
					double result = 1;
					double abs = -1 * b;
					for (int i = 0; i < abs; i++)
					{
						result *= a;
					}
					std::cout << "1/" << result << "\n";
				}
				else
				{
					double result = 1;
					for (int i = 0; i < b; i++)
					{
						result *= a;
					}
					std::cout << result << "\n";
				}
				continue;
			}
			else
			{
				std::cout << "Invalid...\n";
				exit(1);
			}
		}
	} //Basic Math Operations
	else if (choice == 2)
	{
		while (true) {
			int a = 1, b, c, t = 2;
			char x1 = 'x', x2 = 'x', power = '^', oper1, oper2;
			std::cout << "> ";
			std::cin >> a >> x1 >> power >> t >> oper1 >> b >> x2 >> oper2 >> c;
			if (a == 1)
			{
				if ((oper1 == '+') && (oper2 == '+'))
				{
					double discriminant = (b*b) - (4 * a*c); //Discriminant is important, negative = non-factorable
					if (discriminant < 0)
					{
						std::cout << "Non Factorable\n";
						continue;
					}
					else
					{
						double sol1 = ((-1 * b) + sqrt((b*b) - (4 * a*c))) / 2 * a;
						double sol2 = ((-1 * b) - sqrt((b*b) - (4 * a*c))) / 2 * a;
						if ((sol1 < 0) && (sol2 < 0))
						{
							if (isdigit(sol1) || (sol2 - (int)sol2 < 0))
							{
								std::cout << "Non Factorable\n";
								continue;
							}
							else
							{
								std::cout << "(x + " << (-1 * sol1) << ")(x + " << (-1 * sol2) << ")\n";
								continue;
							}
						}
					}
				}
				else if ((oper1 == '-') && (oper2 == '+'))
				{
					double discriminant = (b*b) - (4 * a*c);
					if (discriminant < 0)
					{
						std::cout << "Non Factorable\n";
						continue;
					}
					else
					{
						double sol1 = (b + sqrt((b*b) - (4 * a*c))) / 2 * a;
						double sol2 = (b - sqrt((b*b) - (4 * a*c))) / 2 * a;
						if ((sol1 > 0) && (sol2 > 0))
						{
							if ((sol1 + (int)sol1 < 0) || (sol2 + (int)sol2 < 0))
							{
								std::cout << "Non Factorable\n";
								continue;
							}
							else
							{
								std::cout << "(x - " << (sol1) << ")(x - " << (sol2) << ")\n";
								continue;
							}
						}
					}
				}
			}
			else
			{
				std::cout << "Invalid...\n";
				exit(1);
			}
		}
	}
}
RUNNER PRO AGARIO (275)
Also, sometimes for the assertion failure, it says line 36, other times line 42.
Yawzheek (120)
I don't know if this is the actual problem or not, but I've seen this error pop up several times, and it's ALWAYS related to copying characters into the source code that aren't ASCII standard. In fact, most of the offending characters have been characters that APPEAR to be standard ASCII, but aren't.
cire (8284)
The assertion failure will be in a file other than the one shown here, so providing the line number isn't terribly helpful.

A quick persual of your code shows:

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						double sol1 = ((-1 * b) + sqrt((b*b) - (4 * a*c))) / 2 * a;
						double sol2 = ((-1 * b) - sqrt((b*b) - (4 * a*c))) / 2 * a;
						if ((sol1 < 0) && (sol2 < 0))
						{
							if (isdigit(sol1) || (sol2 - (int)sol2 < 0))


Where you feed a value of type double to isdigit which is likely to set off just such an assertion and probably generates a narrowing conversion warning that you are conveniently ignoring.

TheIdeasMan (6817)
@RUNNER PRO AGARIO

If I could add one very small but useful thing, completely unrelated to your problem:

If you configure your editor to convert tabs to spaces (3 or 4 of them say), then your code will display a lot better here. This site's web page converts tabs to 8 spaces, resulting in excessive indenting.

Hope this Helps :+)
Yawzheek (120)
Where you feed a value of type double to isdigit which is likely to set off just such an assertion and probably generates a narrowing conversion warning that you are conveniently ignoring.


Yup. I would get it reading in Non-ASCII chars into (plain) chars.

OP, if you're using Visual Studio, try stepping through the code. Just start it up with F5, then go through line-by-line with F10. It's EXTREMELY useful for finding the source of problems.

Also, this is the third time I've had to re-type this message, because every time I wanted to say, "F5" I would push the actual F5 key :/
RUNNER PRO AGARIO (275)
Thanks guys you were very helpful. Upon removing isdigit, my code stopped giving the assertion error. I greatly appreciate your time, Thanks!
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