幂函数少返回1个结果 [英] Power function returns 1 less result
问题描述
每当我在该程序中输入数字时,程序都会返回一个比实际结果小1的值...这是什么问题?
Whenever I input a number in this program the program return a value which is 1 less than the actual result ... What is the problem here??
#include<stdio.h>
#include<math.h>
int main(void)
{
int a,b,c,n;
scanf("%d",&n);
c=pow((5),(n));
printf("%d",c);
}
推荐答案
pow ()
返回 double
,即从 double
到 int
正在向零舍入。
pow()
returns a double
, the implicit conversion from double
to int
is "rounding towards zero".
因此,这取决于 pow()的行为
函数。
So it depends on the behavior of the pow()
function.
如果完美,那么没问题,转换是准确的。
If it's perfect then no problem, the conversion is exact.
如果没有:
1)结果稍大,那么转换会将其舍入到期望值。
1) the result is slightly larger, then the conversion will round it down to the expected value.
2)如果结果稍小一点,那么转换将舍入为您所看到的。
2) if the result is slightly smaller, then the conversion will round down which is what you see.
解决方案:
c=lround(pow((5),(n)));
在这种情况下,只要 pow()
的误差小于+ -0.5,您将获得预期的结果。
In this case, as long as pow()
has an error of less than +-0.5 you will get the expected result.
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