Question

C语言pow函数

#include<stdio.h>
#include<math.h>
#include "stdlib.h"
void f(long n)
{printf("%f\t", pow(n,3));
printf("%lf\t", pow(n,3));
printf("%ld\t", (long)pow(n,3));
printf("结果是:%I64d\t",(long long int )pow(n,3));
printf("%d\n", (int)pow(n,3));
}
main()
{long i=5;
printf("%f\t", pow(5,3));
printf("%lf\t", pow(5,3));
printf("%ld\t", (long)pow(5,3));
printf("结果是:%I64d\t",(long long int )pow(5,3));
printf("%d\n", (int)pow(5,3));
system("pause");

printf("%f\t", pow(i,3));
printf("%lf\t", pow(i,3));
printf("%ld\t", (long)pow((int)i,3));
printf("结果是:%I64d\t",(long long int )pow(i,3));
printf("%d\n", (int)pow(i,3));
system("pause");

f(i);
system("pause");
}
这个程序为什么只有前一个输出答案正确,后面的都不正确呢?
我想问的是为什么只有第一组输出语句pow(5,3)输出结果为125,后面二组,输出类型不为实型的时候输出结果为124?

Answer 1

两个都可以，刚才已经运行了程序。
#include
<stdio.h>
#include
<math.h>
int
main(int
argc,
char
*argv[])
{
float
c
=
4
*
pow(10,4);
int
x
=
10,
y
=
4;
float
z;
z
=
4
*
pow(x,y);
printf("%f\n%f\n",
c,
z);
return
0;
}

Answer 2

double
pow(
double
x,
double
y
);
都合法，但最好都转成double用

Answer 3

Answer 4

printf("%f\n", pow(2,3));