回答編集履歴
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VC\+\+2010 SP1 インストール記念に質問者の希望とは違うけど検証結果証跡として記録
test
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@@ -47,3 +47,187 @@
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```
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```C
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// TEST01.cpp : コンソール アプリケーションのエントリ ポイントを定義します。
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//
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#include "stdafx.h"
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#include <stdio.h>
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#include <stdlib.h>
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typedef unsigned char uchar;
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typedef union bitfloat_t {
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float value;
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uchar bytes[sizeof(float)];
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} bitfloat_t;
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#define FLOATLEN sizeof(float) * 8
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float bits2float(uchar* buffer);
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void clearMem(uchar* buffer, int size);
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void float2bits(float v, uchar* buffer);
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void test(char *title, float val);
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int _tmain(int argc, _TCHAR* argv[])
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{
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test("テスト１", 1e26F);
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test("テスト２", 1.1234567890123456789F);
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test("テスト３", 1.1234567e10F);
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return 0;
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}
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void test(char *title, float val) {
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bitfloat_t v;
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uchar buffer[FLOATLEN +1];
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v.value = val;
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float2bits(val, buffer);
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printf("%s\n", title);
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printf("実数値→変換：%f => %s\n", val, buffer);
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float ff = bits2float(buffer);
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printf("変換→実数値：%s => %f(%e)\n", buffer, ff, ff);
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fgetc(stdin);
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}
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void clearMem(uchar* buffer, int size) {
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for (int i=0;i < size;i++) buffer[i] = 0;
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}
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float bits2float(uchar* buffer) {
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bitfloat_t vv;
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clearMem(vv.bytes, sizeof(vv));
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int maxLen = FLOATLEN;
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uchar bit = 0;
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for (int i=0;i < maxLen;i++) {
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if (bit == 0) bit = 0x80;
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vv.bytes[i / 8] |= buffer[i] == '1' ? bit : 0;
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bit >>= 1;
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}
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return vv.value;
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}
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void float2bits(float v, uchar* buffer) {
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bitfloat_t vv;
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vv.value = v;
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int maxLen = FLOATLEN;
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buffer[maxLen] = 0;
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uchar bit = 0;
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for (int i=0;i < maxLen;i++) {
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if (bit == 0) bit = 0x80;
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buffer[i] = vv.bytes[i / 8] & bit ? '1' : '0';
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bit >>= 1;
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}
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}
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```
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VC++2010 Sp1 当てた記念に残しておきます。
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