@nifty:FHPG:お役立ち:JavaScriptのおもちゃ箱:小数点の扱い２

ソース記述内容

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html lang="ja">
<head>
<title>小数点の扱い２</title>
<script type="text/javascript">
<!--

var MAXLENGTH = 10
var OFF = 4
var SIGN = 0
var LW = 1
var LW1 = 2
var LW2 = 3

function Structure(n)
{
    var res = new Array(OFF+n)
    var i
    for (i = 0; i <= OFF+n; i++) {
        res[i] = 0
    }
    res[SIGN] = 1
    return res
}

function mul(a, b)
{
    var i, j
    var c = new Structure(a[LW]+b[LW])
    if (a[LW]*b[LW] == 0) {
        return c
    }
    c[LW] = a[LW]+b[LW]
    c[SIGN] = a[SIGN]*b[SIGN]
    c[LW2] = a[LW2]+b[LW2]
    c[LW1] = c[LW]-c[LW2]
    for (j = 0; j < b[LW]; j++) {
        for (i = 0; i < a[LW]; i++) {
            c[OFF+i+j+1] += a[OFF+i] * b[OFF+j]
        }
    }
    carry(c)
    norm(c)
    return c
}

function carry(c)
{
    var i
    for (i = c[LW]-1; i >= 0; i--) {
        if (c[OFF+i] >= 10) {
            c[OFF+i-1] += Math.floor(c[OFF+i]/10)
            c[OFF+i]    %= 10
        }
    }
}

function norm(c)
{
    var i
    while (c[OFF] == 0 && c[LW1] > 0) {
        c[LW]--
        c[LW1]--
        for (i = 0; i < c[LW]; i++) {
            c[OFF+i] = c[OFF+i+1]
        }
    }
    c.length = (c[LW] = c[LW1]+c[LW2])+OFF
}

function output(y)
{
    var i, res = ""

    if (y[LW] == 0) {
        return "0"
    }

    if (y[SIGN] == -1) {
        res += "-"
    }

    if (y[LW1] <= 0) {
        res += "0"
    }
    else {
        for (i = 0; i < y[LW1]; i++) {
            res += y[OFF+i]
        }
    }

    res += "."

    if (y[LW1] == y[LW]) {
        res += "0"
    }
    else {
        for (i = 0; i < y[LW2]; i++) {
            res += y[OFF+y[LW1]+i]
        }
    }
    return res
}

function get(constant)
{
    var i, l, sw = 1, lw = 0, w1 = 0, w2 = 0, is = 1, non_zero
    var res = new Structure(l = constant.length)
    for (i = 0; i < l; i++) {
        c = constant.charAt(i)
        if (c == '-') {
            sw = -1
        }
        else if (c == '.') {
            is = 2
        }
        else {
            res[OFF+(lw++)] = c
            if (is == 1) {
                w1++
            }
            else {
                w2++
            }
        }
    }
    non_zero = 0
    for (i = 0; i < lw; i++) {
        if (res[OFF+i] != 0) {
            non_zero = 1
            break
        }
    }
    if (non_zero == 0) {
        lw = w1 = w2 = 0
    }
    res[LW] = lw
    res[LW1] = w1
    res[LW2] = w2
    res[SIGN] = sw
    return res
}

function result()
{
    document.f.right.value = output(mul(get(document.f.left.value), 
get(document.f.center.value)))
}
// -->
</script>
</head>
<body>
<table border="0" align="center">
  <tr>
    <td align="center">
      <form name="f">
        <input name="left" type="Text" size="60" maxlength="60" style="text-align:right">
        <p>×</p>
        <input name="center" type="Text" size="60" maxlength="60" style="text-align:right">
        <p>=</p>
        <input name="right" type="Text" size="80" maxlength="80" style="text-align:right">
        <input name="Input" type=Button value="push" onClick="result()">
        <input name="Reset" type=Reset value="reset">
      </form>
    </td>
  </tr>
</table>
</body>
</html>
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小数点の扱い２

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ソース記述内容
