大家帮我看看这段C语言错在哪

Question

本来是计算折扣的，但是无论输入数字是多少，结果都是0，错哪了？
#include <stdio.h>
int main(void)
{
int number=0;
double value=0.0;
double discount=0.0;
value=(1-discount)*number*5;
printf("please enter the number of goods\n");
scanf("%d",&number);
if (number<0)
printf("your enter is error!");
else{
if(number>=50)
{discount=0.15;
printf("your goods value is $%lf",value);}
else if(number>=30)
{discount=0.10;
printf("your goods value is $%lf",value);}
else
{discount=0.0;
printf("your goods value is $%lf",value);}
}
}

Answer 1

因为你的value这个参数没有参加你定义的那个运算value=(1-discount)*number*5
……所以一直是初始化的值，也就是0

Answer 2

#include <stdio.h>
int main(void)
{
int number=0;
double value=0.0;
double discount=0.0;
printf("please enter the number of goods\n");

scanf("%d",&number);

if (number<0)
printf("your enter is error!");
else
{
if(number>=50)
{
discount=0.15;
value=(1-discount)*number*5;
printf("your goods value is $%lf",value);}
else if(number>=30)
{
discount=0.10;
value=(1-discount)*number*5;
printf("your goods value is $%lf",value);}
else
{
discount=0.0;
value=(1-discount)*number*5;
printf("your goods value is $%lf",value);}
}
}

Answer 3

value=(1-discount)*number*5;
位置不对，可以说相当于一个常量了。

Answer 4

value=(1-discount)*number*5; 这里的话value一直等于0。