Thread: Help with typecasting

  1. #1
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    Exclamation Help with typecasting

    The assignment asks to input these values:

    D = Investment Amount (5000)
    P = Interest (5.25)
    Y = Number of Years (2.25)
    M = Conversions/Year (4)

    It tells me to use float for interest, and int for the rest.
    I have to use this formula to calculate the Maturity value (S)
    S = D ( 1 + P/M) to the power of YM

    Using the data above S is suppose to equal 5622.60
    When I debug I get 5065.62.

    I think I have made an error in typecasting int to double or float to double

    Code:
    // MaturityCalc.cpp : Defines the entry point for the console application.
    //
    
    #include "stdafx.h"
    #include <iostream>
    #include <math.h>
    
    using namespace std;
    
    int _tmain(int argc, _TCHAR* argv[])
    {
    	int m, y, d;
    	double s;
    	float p;
    
    	//keyboard input
    	cout << "Please input the following information";
    	cout << endl;
    	cout << "Investment Amount: ";
    	cin >> d;
    	cout << endl;
    	cout << "Interest Rate: ";
    	cin >> p;
    	cout << endl;
    	cout << "Conversions/Year: ";
    	cin >> m;
    	cout << endl;
    	cout << "Number of Years: ";
    	cin >> y;
    	cout << endl;
    	//end keyboard entry
    	
    	y = y * m;
    	p = 1 + (p/100)/m;
    	pow ((double) p , (double)y);
    	s = d * p;
    	cout << "This is the result: " << (double)s;
    
    	system ("pause");
    
    	return 0;
    }

    Note: This is my second assignment, first week of C++, I have very little knowledge of this.

    Any help is appreciated.

  2. #2
    Jack of many languages Dino's Avatar
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    If you have 2.25 years, then years needs to be a float or double.
    Mainframe assembler programmer by trade. C coder when I can.

  3. #3
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    Thanks for that, it fixed a glitch that was skipping y, but I'm still getting the same answer.

  4. #4
    Jack of many languages Dino's Avatar
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    Are you getting (and ignoring) any compiler warnings?

    Did you fix the data type or just cast around it?
    Mainframe assembler programmer by trade. C coder when I can.

  5. #5
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    No compiler errors. I'm not sure what your second comment means, sorry.

  6. #6
    Jack of many languages Dino's Avatar
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    Post your code please.
    Mainframe assembler programmer by trade. C coder when I can.

  7. #7
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    Code:
    // MaturityCalc.cpp : Defines the entry point for the console application.
    //
    
    #include "stdafx.h"
    #include <iostream>
    #include <math.h>
    
    using namespace std;
    
    int _tmain(int argc, _TCHAR* argv[])
    {
    	int m, d;
    	double s;
    	float p, y;
    
    	//keyboard input
    	cout << "Please input the following information";
    	cout << endl;
    	cout << "Investment Amount: ";
    	cin >> d;
    	cout << endl;
    	cout << "Interest Rate: ";
    	cin >> p;
    	cout << endl;
    	cout << "Conversions/Year: ";
    	cin >> m;
    	cout << endl;
    	cout << "Number of Years: ";
    	cin >> y;
    	cout << endl;
    	//end keyboard entry
    	
    	y = y * m;
    	p = 1 + (p/100)/m;
    	pow ((double) p , (double)y);
    	s = d * p;
    	cout << "This is the result: " << (double)s;
    
    	system ("pause");
    
    	return 0;
    }

  8. #8
    and the Hat of Guessing tabstop's Avatar
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    Were you planning to store the result of the pow anywhere handy?

  9. #9
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    Haha, that was it! Thank you very much!

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