VC中float型浮点数问题

1、VC+中float型浮点数问题float型数据在显示时会因为精度问题而造成不正确的四舍五入问题，由于float型的有效位为6位，所以当一个数据的整数部分越大，则小数部分的精度越低。数据测试结果原始数据（float）内存中的数据显示两位小数显示三位小数>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测试结果分析1、 当数据>100,000时，由测试结果可知其小数位的有效精度为十分位，即小数点后第一位是精确的，而后面的小数位则存现近似结果，如。如果以double类型存储，则可以非常精确的显示。如101000.347，则可精确的显示为101000.3470000。2、 当数据>10,000时，由测试结果可知其小数位的有效精度为百分位，即小数点后前两位是精确的，而后面的小数位则存现近似结果。3、 当数据<10,000时，由测试结果可知其小数位的有效精度依然为百分位，即小数点后前两位是精确的，而后面的小数位则存现近似结果。但数据的精度误差远远