问我正在将一些C++标准函数移植到C#中进行验证(匹配结果)。

EN

/// <summary>
/// C# port of C++ functions
/// </summary>
public static class LegacyEx
{
    const int _CVTBUFSIZE=50;
    /// <summary>
    /// Port of C++ _fcvt() function. See http://sydney.edu.au/engineering/it/~kev/pp/RESOURCES/cplusplus/ref/cstdlib/fcvt.html
    /// </summary>
    /// <param name="value">Floating point value to be converted to a string.</param>
    /// <param name="digits">Number of digits to be returned. If this is greater than the number of representable digits the rest of the string is padded with zeros. If this is smaller the low-order digit is rounded.</param>
    /// <param name="decimal">Pointer to an int where to store the decimal-point position respect to the beginning of the string. 0 or less indicates that the decimal point lies to the left of the digits.</param>
    /// <param name="sign">Pointer to an int that receives the sign indicator: 0 means positive sign, non-zero means negative.</param>
    /// <returns>A null-terminated buffer with the legth specified by num that contains the digits of the value.</returns>
    static char[] _fcvt(double value, int digits, out int @decimal, out int sign)
    {
        sign=value>0?0:1; // 0=positive, 1=otherwise
        char[] buffer=new char[_CVTBUFSIZE];
        value=Math.Round(Math.Abs(value),digits); //remove sign and round digits
        string t=value.ToString();
        @decimal=t.IndexOf('.')+@sign; //find index of decimal point
        t=t.Replace(".", string.Empty); //remove decimal point
        Array.Copy(t.ToCharArray(), buffer, t.Length);
        return buffer;
    }

    /// <summary>
    /// Port of C++ ltoa() function. See http://rp-www.cs.usyd.edu.au/~kev/pp/RESOURCES/cplusplus/ref/cstdlib/ltoa.html
    /// </summary>
    /// <param name="value">Value to be represented as a string.</param>
    /// <param name="buffer">Buffer where to store the resulting string.</param>
    /// <param name="radix">Numeral radix in which value has to be represented, between 2 and 36.</param>
    /// <returns> A buffer containing the string.</returns>
    static char[] ltoa(long value, ref char[] buffer, int radix)
    {
        // convert value to string of base radix
        string text=Convert.ToString(value, radix);
        // insert result into buffer
        char[] array=text.ToCharArray();
        Array.Copy(array, buffer, array.Length);
        return array;
    }

    /// <summary>
    /// Port of C++ atoi() function. See http://rp-www.cs.usyd.edu.au/~kev/pp/RESOURCES/cplusplus/ref/cstdlib/atoi.html
    /// </summary>       
    /// <param name="text">String representing an integer number.</param>
    /// <returns>The converted integer value of the input string.</returns>
    static int atoi(string text)
    {
        // get rid of whitespace
        text=text.Trim(); 
        // consider up to last digit. This will fail with "12A3" for example
        int count =text.LastIndexOfAny("0123456789".ToCharArray());
        text=text.Substring(0, count);
        int x=0;
        int.TryParse(text, out x);
        return x;
    }

    /// <summary>
    /// Port of CString(char[]) constructor
    /// </summary>
    /// <param name="buffer">A null terminated buffer for the string definition.</param>
    /// <returns>The string value from the buffer.</returns>
    static string String(char[] buffer)
    {
        int count=Array.IndexOf(buffer, '\0');
        if(count<0) { count=buffer.Length; }
        return new string(buffer, 0, count);
    }
} // LegacyEx