Thread: Set Precision in C# Builder

  1. #1
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    Set Precision in C# Builder

    Hi,


    I've written a program in C++ Builder 6, in order to generate a code for PSpice software. In this code I've used a for loop like this:

    Code:
    for (double i=deltax/2; i<Lx; i=i+deltax)
    {
    Memo1->Lines->Add("** i= " + (AnsiString)i);
    
    
    }

    deltax and Lx are doubles. My problem is that after some iterations, the value of i increases by a very small extent and this small error is troublesome for me. for example when I expect i=12.08, it says i=12.08000000000001.


    As a solution, I want i to have only 2 digits as decimals. How can I write this?

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  3. #3
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    Question looks verbatim to the answers question.

  4. #4
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    Here is the solution;

    solution 1... work in integers as if *100. Insert the decimal with a custom print routine (cout << value/100 << "." << value % 100. This keeps your precision pristine internally, so you don't accumulate roundoff errors (important if this is money, for example).

    solution 2: just change the print statement. You may want to bump round it (what if you had gotten 12.079999999999999999 instead? you need to bump it up to 12.08 ) first. That looks like std::cout << std::setprecision(2) << value << '\n'; or
    if value >= 0
    std::cout << std::setprecision(2) << value + 0.001 << '\n';
    else
    std::cout << std::setprecision(2) << value - 0.001 << '\n';

    [COLOR=#000000][FONT=verdana]if I did all that correctly. Hopefully you get the idea.
    Last edited by Salem; 11-12-2017 at 02:25 AM. Reason: spammy links deleted

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