浮点不能准确地打印 [英] Floating point does not print accurately

问题描述

  

可能重复：结果
  用C 浮点问题

 ＃包括LT＆;＆stdio.h中GT;
主要（）
{
        诠释A，B;
        浮F;
        scanf函数（％2D％3D％4F，＆安培;一，和b，＆安培; F）;
        的printf（％D％F，A，B，F）;
}
 

当我运行这个程序，输入2 4 56.8，它给输出2 4 56.799999 .....但我希望2 4 56.8 ....为什么会这样？

解决方案

这是正确的。浮点数是近似值。正如0.33333333是一个近似1/3，56.7999999是56.8近似值。有0.1没有确切的浮点重新presentation。

请参阅一些什么已经被写入：

• http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html


• http://www.hack3r.com/forum-topic/what-every-programmer-should-know-about-floating-point-arithmetic

Possible Duplicate:
Floating point issue in C

#include<stdio.h>
main()
{
        int a,b;
        float f;
        scanf("%2d%3d%4f",&a,&b,&f);
        printf("%d %d %f",a,b,f);
}

When i run this program and input 2 4 56.8 ,it gives output 2 4 56.799999.....but I would expect 2 4 56.8....why is it so???

解决方案

That is correct. Floating point numbers are approximations. Just as 0.33333333 is an approximation to 1/3, 56.7999999 is an approximation for 56.8. There is no exact floating point representation for 0.1.

See some of what has been written:

• http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
• http://www.hack3r.com/forum-topic/what-every-programmer-should-know-about-floating-point-arithmetic

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