scanf函数为什么取不到双精度浮点数？

[meitianjiaban]

/* 递归求n个数的积 */
/* 下面a[i]的取值是乱码 */
#include <stdio.h>
#include <stdlib.h>

double Ave(double *,int );

int main()
{

int i=0,n=0;
double aveval=0.0;
double *a=NULL;

printf("Please enter the count of numbers :\n");
scanf("%d",&n);

if(NULL==(a=(int *)malloc( sizeof(int)*n )))
{

printf(" Application space failure. ");
exit(1);
}

printf("Please input %d numbers:\n",n);
for(i=0;i<n;i++)
{
printf("It's the %dth number:",i+1);
scanf("%f",&a[i]); /* 这儿有问题 */
}
for(i=0;i<n;i++)
{
printf("It's the %dth number:%f\n",i+1,a[i]);/* */
}

aveval=Ave(a,n-1);

free(a);

printf("avevalue=%f\n\n",aveval);

printf("Please press any key to quit..\n");

return 0;
}

double Ave(double *a,int n)
{
if(n==0)
return a[0];
else
{

return (a[n]+Ave(a,n-1)*n)/(n+1); /* 个数必须加1，由于数组作用 */
}
}

[Athenacle_]

scanf("%lf",&a[i]);

[Jake443403168]

#include <stdio.h>
#include <stdlib.h>

double Ave(double *,int );

int main()
{

  int i=0,n=0;
  double aveval=0.0;
  double *a=NULL;

  printf("Please enter the count of numbers :\n");
  scanf("%d",&n);

  if(NULL==(a=(double *)malloc( sizeof(double)*n )))//写double把，你的a是double类型的
  {

  printf(" Application space failure. ");
  exit(1);
  }

  printf("Please input %d numbers:\n",n);
  for(i=0;i<n;i++)
  {
  printf("It's the %dth number:",i+1);
  scanf("%lf",&a[i]); /* 这儿有问题 */       //双精度用%lf，单精度用f
  }
  for(i=0;i<n;i++)
  {
  printf("It's the %dth number:%f\n",i+1,a[i]);/* */
  }

  aveval=Ave(a,n-1);

  free(a);

  printf("avevalue=%f\n\n",aveval);

  printf("Please press any key to quit..\n");

  return 0;
}

double Ave(double *a,int n)
{
  if(n==0)
  return a[0];
  else
  {

  return (a[n]+Ave(a,n-1)*n)/(n+1); /* 个数必须加1，由于数组作用 */
  }
}

[meitianjiaban]

代码重发遍，上面代码有点小问题
/* 递归求n个数的积 */
#include <stdio.h>
#include <stdlib.h>

double Ave(double *,int );

int main()
{

int i=0,n=0;
double aveval=0.0;
double *a=NULL;

printf("Please enter the count of numbers :\n");
scanf("%d",&n);
if(NULL==(a=(double *)malloc( sizeof(double)*n )))
{

printf(" Application space failure. ");
exit(1);
}

printf("Please input %d numbers:\n",n);
for(i=0;i<n;i++)
{
printf("It's the %dth number:",i+1);
scanf("%f",&a[i]); /* 这儿有问题? */
}
for(i=0;i<n;i++)
{
printf("It's the %dth number:%f\n",i+1,a[i]);/* */
}

aveval=Ave(a,n-1);

free(a);
printf("avevalue=%f\n\n",aveval);
printf("Please press any key to quit..\n");
return 0;
}

double Ave(double *a,int n)
{
if(n==0)
return a[0];
else
return (a[n]+Ave(a,n-1)*n)/(n+1); /* 个数必须加1，由于数组作用 */
}

[meitianjiaban]

知道了双精度必须是"%lf"。调试成功
[Quote=引用 1 楼 athenacle_ 的回复:]
scanf("%lf",&a[i]);
[/Quote]

[meitianjiaban]

知道了双精度必须是"%lf"。调试成功

[Quote=引用 2 楼 jake443403168 的回复:]
C/C++ code


#include <stdio.h>
#include <stdlib.h>

double Ave(double *,int );

int main()
{

int i=0,n=0;
double aveval=0.0;
double *a=NULL;

printf("Please enter the count of……
[/Quote]

[shexinwei]

其他子程序没看，关键问题在于内存分配错误，分配的是int型空间，而应该是double类型

#include <stdio.h>
#include <stdlib.h>

double Ave(double *,int );

int main()
{

  int i=0,n=0;
  double aveval=0.0;
  double *a=NULL;

  printf("Please enter the count of numbers :\n");
  scanf("%d",&n);

  if(NULL==(a=(int *)malloc( sizeof(int)*n )))  //修改为： a=(double *)malloc( sizeof(double)*n )
  {

  printf(" Application space failure. ");
  exit(1);
  }

  printf("Please input %d numbers:\n",n);
  for(i=0;i<n;i++)
  {
  printf("It's the %dth number:",i+1);
  scanf("%f",&a[i]); /* 这儿有问题 */
  }
  for(i=0;i<n;i++)
  {
  printf("It's the %dth number:%f\n",i+1,a[i]);/* */
  }

  aveval=Ave(a,n-1);

  free(a);

  printf("avevalue=%f\n\n",aveval);

  printf("Please press any key to quit..\n");

  return 0;
}

double Ave(double *a,int n)
{
  if(n==0)
  return a[0];
  else
  {

  return (a[n]+Ave(a,n-1)*n)/(n+1); /* 个数必须加1，由于数组作用 */
  }
}