mpmath高精度浮点数四则运算、比较、格式化简单封装 - QTCN开发网

/**
* mpmath浮点数精确计算简单封装, 依赖于GMP库
* (C) 2012 by XChinux@163.com
*/
#include <sstream>
#include <gmp.h>
#include "mpmath.hpp"

namespace ChinuxTeam
{
enum mp_op_t {op_add, op_sub, op_mul, op_div};
std::string mp_op(mp_op_t op, const std::string &arg1,
        const std::string &arg2, int prec);

std::string mp_add(const char *arg1, const char *arg2, int prec)
{
    return mp_op(op_add, std::string(arg1), std::string(arg2), prec);
}

std::string mp_sub(const char *arg1, const char *arg2, int prec)
{
    return mp_op(op_sub, std::string(arg1), std::string(arg2), prec);
}

std::string mp_mul(const char *arg1, const char *arg2, int prec)
{
    return mp_op(op_mul, std::string(arg1), std::string(arg2), prec);
}

std::string mp_div(const char *arg1, const char *arg2, int prec)
{
    return mp_op(op_div, std::string(arg1), std::string(arg2), prec);
}

std::string mp_fmt(const char *arg1, int prec,
        bool show_thousand_digit_symbol)
{
    return mp_fmt(std::string(arg1), prec, show_thousand_digit_symbol);
}

int mp_comp(const char *arg1, const char *arg2)
{
    return mp_comp(std::string(arg1), std::string(arg2));
}

//-------------------------------------------------------------------

QString mp_add(const QString &arg1, const QString &arg2, int prec)
{
    return QString::fromStdString(mp_op(op_add, arg1.toStdString(),
                arg2.toStdString(), prec));
}

QString mp_sub(const QString &arg1, const QString &arg2, int prec)
{
    return QString::fromStdString(mp_op(op_sub, arg1.toStdString(),
                arg2.toStdString(), prec));
}

QString mp_mul(const QString &arg1, const QString &arg2, int prec)
{
    return QString::fromStdString(mp_op(op_mul, arg1.toStdString(),
                arg2.toStdString(), prec));
}

QString mp_div(const QString &arg1, const QString &arg2, int prec)
{
    return QString::fromStdString(mp_op(op_div, arg1.toStdString(),
                arg2.toStdString(), prec));
}

QString mp_fmt(const QString &arg1, int prec,
        bool show_thousand_digit_symbol)
{
    return QString::fromStdString(mp_fmt(arg1.toStdString(), prec,
                show_thousand_digit_symbol));
}

int mp_comp(const QString &arg1, const QString &arg2)
{
    return mp_comp(arg1.toStdString(), arg2.toStdString());
}

//----------------------------------------------------------------------

std::string mp_add(const std::string &arg1, const std::string &arg2, int prec)
{
    return mp_op(op_add, arg1, arg2, prec);
}

std::string mp_sub(const std::string &arg1, const std::string &arg2, int prec)
{
    return mp_op(op_sub, arg1, arg2, prec);
}

std::string mp_mul(const std::string &arg1, const std::string &arg2, int prec)
{
    return mp_op(op_mul, arg1, arg2, prec);
}

std::string mp_div(const std::string &arg1, const std::string &arg2, int prec)
{
    return mp_op(op_div, arg1, arg2, prec);
}

int mp_comp(const std::string &arg1, const std::string &arg2)
{
    std::string::size_type pos1 = arg1.find_last_of(".");
    std::string::size_type pos2 = arg2.find_last_of(".");
    int prec1 = pos1 == std::string::npos ? 0 : (arg1.size() - pos1 - 1);
    int prec2 = pos2 == std::string::npos ? 0 : (arg2.size() - pos2 - 1);

    mpf_t f1, f2;
    mpf_init2(f1, prec1);
    mpf_init2(f2, prec2);
    mpf_set_str(f1, arg1.c_str(), 10);
    mpf_set_str(f2, arg2.c_str(), 10);
    int ret = mpf_cmp(f1, f2);
    mpf_clear(f1);
    mpf_clear(f2);
    return ret;
}

std::string mp_fmt(const std::string &arg1, int prec,
        bool show_thousand_digit_symbol)
{
    mpf_t f1;
    mpf_init2(f1, prec);
    mpf_set_str(f1, arg1.c_str(), 10);

    std::ostringstream fmt;
    fmt << "%." << prec << "Ff";

    char *ret;
    int len = gmp_asprintf(&ret, fmt.str().c_str(), f1);

    mpf_clear(f1);

    std::string str(ret);
    __gmp_free_func(ret, len);
    ret = NULL;

    if (!show_thousand_digit_symbol)
    {
        return str;
    }

    int pos = str.size() - (prec > 0 ? (4 + prec) : 3);
    while (pos > 0)
    {
        str.insert(pos, 1, ',');
        pos -= 3;
    }
    return str;
}

std::string mp_op(mp_op_t op, const std::string &arg1,
        const std::string &arg2, int prec)
{
    std::string::size_type pos2 = arg2.find_last_of(".");
    int prec2 = pos2 == std::string::npos ? 0 : (arg2.size() - pos2 - 1);

    mpf_t f2;
    mpf_init2(f2, prec2);
    mpf_set_str(f2, arg2.c_str(), 10);

    if (op == op_div)
    {
        if (mpf_cmp_si(f2, 0) == 0)
        {
            mpf_clear(f2);
            return std::string();
        }
    }

    std::string::size_type pos1 = arg1.find_last_of(".");
    int prec1 = pos1 == std::string::npos ? 0 : (arg1.size() - pos1 - 1);

    mpf_t f1, f3;
    mpf_init2(f1, prec1);
    mpf_init2(f3, prec);
    mpf_set_str(f1, arg1.c_str(), 10);
    switch (op)
    {
        case op_add:
            mpf_add(f3, f1, f2);
            break;
        case op_sub:
            mpf_sub(f3, f1, f2);
            break;
        case op_mul:
            mpf_mul(f3, f1, f2);
            break;
        case op_div:
            mpf_div(f3, f1, f2);
            break;
        default:;
    }

    std::ostringstream fmt;
    fmt << "%." << prec << "Ff";

    char *ret;
    int len = gmp_asprintf(&ret, fmt.str().c_str(), f3);

    mpf_clear(f1);
    mpf_clear(f2);
    mpf_clear(f3);

    std::string str(ret);
    __gmp_free_func(ret, len);
    ret = NULL;
    return str;
}
}