VC中float型浮點數(shù)問題

1、VC+中float型浮點數(shù)問題float型數(shù)據(jù)在顯示時會因為精度問題而造成不正確的四舍五入問題，由于float型的有效位為6位，所以當(dāng)一個數(shù)據(jù)的整數(shù)部分越大，則小數(shù)部分的精度越低。數(shù)據(jù)測試結(jié)果原始數(shù)據(jù)（float）內(nèi)存中的數(shù)據(jù)顯示兩位小數(shù)顯示三位小數(shù)>100000101000.340347101000.3437500101000.34101000.344101000.348355101000.3515625101000.35101000.352101000.356363101000.3593750101000.36101000.360101000.364371101000.3671875

2、101000.37101000.367>1000011000.34311000.342773411000.3411000.34311000.34411000.343750011000.3411000.34411000.34511000.344726611000.3411000.34511000.34611000.345703111000.3511000.346>10001000.3431000.34301761000.341000.3431000.3441000.34399411000.341000.3441000.3451000.34497071000.341000.345100

3、0.3461000.34600831000.351000.346>100100.343100.3430176100.34100.343100.344100.3439941100.34100.344100.345100.3449707100.34100.345100.346100.3460083100.35100.346>1010.34310.343017610.3410.34310.34410.343994110.3410.34410.34510.344970710.3410.34510.34610.346008310.3510.346>11.3431.34301761.34

4、1.3431.3441.34399411.341.3441.3451.34497071.341.3451.3461.34600831.351.346<10.3430.34301760.340.3430.3440.34399410.340.3440.3450.34497070.340.3450.3460.34600830.350.346測試結(jié)果分析1、 當(dāng)數(shù)據(jù)>100,000時，由測試結(jié)果可知其小數(shù)位的有效精度為十分位，即小數(shù)點后第一位是精確的，而后面的小數(shù)位則存現(xiàn)近似結(jié)果，如。如果以double類型存儲，則可以非常精確的顯示。如101000.347，則可精確的顯示為101000.3470000。2、 當(dāng)數(shù)據(jù)>10,000時，由測試結(jié)果可知其小數(shù)位的有效精度為百分位，即小數(shù)點后前兩位是精確的，而后面的小數(shù)位則存現(xiàn)近似結(jié)果。3、 當(dāng)數(shù)據(jù)<10,000時，由測試結(jié)果可知其小數(shù)位的有效精度依然為百分位，即小數(shù)點后前兩位是精確的，而后面的小數(shù)位則存現(xiàn)近似結(jié)果。但數(shù)據(jù)的精度誤差遠(yuǎn)遠(yuǎn)