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Thread: C++ Help. CAN'T FIGURE IT OUT =(

10122007, 05:50 AM #1
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C++ Help. CAN'T FIGURE IT OUT =(
I have been working on this simple program for hours now and still can't figure out my problem. Could someone please lend me some help? Thanks in advance.
Instructions:
Write a complete C++ program which will prompt the user for the three coefficients of a quadratic polynomial, and will then compute and display the two zeros of that polynomial. Use the quadratic formula.
Code:#include <iostream.h> #include <math.h> //Find the 2 zeros using the quadratic formula. void main (void) { float a = 0.0; float b = 0.0; float c = 0.0; float quadraticFormula; float quadraticFormula2; system("cls"); cout << "Enter 1st Coefficient: "; cin >> a; cout << "Enter 2nd Coefficient: "; cin >> b; cout << "Enter 3rd Coefficient: "; cin >> c; if (a != 0 & b*b4*a*c > 0) { quadraticFormula = b + sqrt(b*b4*a*c) / (2* a); //Calculates the + of the zero quadraticFormula2 = b  sqrt(b*b4*a*c) / (2 * a); //Calculates the  of the zero cout << "First Zero (+): " << quadraticFormula << endl; cout << "Second Zero (): " << quadraticFormula2 << endl; } else { system("PAUSE"); cout << endl; cout << "Error! Press Any Key to Terminate..."; }//end if return; } //end main
Last edited by odinzu; 10122007 at 06:40 AM.
10122007, 06:16 AM
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Rather than forcing people to guess at the purpose of your program and why it doesn't work it'd be helpful if you told us what you're trying to do, whether you're getting compile errors or runtime errors etc.
Help us help you.
10122007, 06:40 AM
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alright, updated. Is that ok?
10122007, 09:14 AM
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I guess not =\
10122007, 07:13 PM
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You still haven't stated what the problem is. Is it not calculating properly? Is it not compiling? Is crashing when you run it?
At first glance, try checking your equations.
i.e. b + sqrt((b*b)(4*a*c)) / (2* a)
Some bracketing may help (like above) to make sure the order of computation is being done correctly.
10122007, 09:05 PM
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That does not compile in VC++ due to the following:
 .h in the includes
 math include had to be changed to cmath
 missing namespace
 missing second ampersand in if()
If you're compiling with GCC you might not need to do 1, or 2, though. Even after it compiles the formula doesn't seem to do anything, but I might not be entering numbers that you're going to be using. Follow Gox's suggestion for using parenthesis to be sure the equation is executed in the proper order.
10122007, 11:50 PM
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10132007, 06:47 AM
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Glad you got it working!