高手请进。一道做计算器程序的难题

//注：除法只算出整除橘虚的结果。

#include<stdio.h>

#include<stdlib.h>

#include <time.h>

int add(int x,int y)

{printf("%d + %d =",x,y)

return x+y}

int sub(int x,int y)

{printf("%d - %d =",x,y)return x-y}

int mul(int x,int y)

{printf("%d * %d =",x,y)return x*y}

int dec(int x,int y)

{printf("%d / %d =",x,y)return x/y}

int mod(int x,int y)

{printf("%d % %d =",x,y)return x%y}

void fun(int f)

{

int n,x,y,z,t,result,sum=0

srand((unsigned)time(NULL))

printf("请选择答题的个数:\n")

scanf("%d",&n)

for(int i=0i<ni++)

{

x=rand()%100

y=rand()%100

if(x<y &&f==2)

{t=xx=yy=t}

if(f==3||f==4)

{while(!x){x=rand()%100}

while(!y){y=rand()%100}}

switch(f)

{

case 1:

result=add(x,y)break

case 2:

result=sub(x,y)break

case 3:

result=mul(x,y)break

case 4:

result=dec(x,y)break

case 5:

result=mod(x,y)break

}

scanf("%d",&z)

if(result==z)

{printf("正确!\n")sum++}

else

printf("错误!应该是%d\n",result)

}

printf("\行告n正确率为%f%%\n/////////////////////////////////\n\n",100.0*sum/n)

fflush(stdin)

}

void main()

{

printf("/////////////////////////////////\n")

printf(" 计算软件\n")

printf("//////////////////////////////////\n\n")

int ch

while(1)

{

printf("请选择圆带燃题型--加(1),减(2),乘(3),除(4),求余(5),退出(6): ")

scanf("%d",&ch)

if(ch==1||ch==2||ch==3||ch==4||ch==5)

fun(ch)

else if(ch==6)

exit(0)

else

printf("错误!\n")

}

}

不懂请追问

#include <stdio.h>

#include <string.h>

int main()

{

__int64 n,m

int c,jin,bg,i

int num[21]

while(scanf("%lld",&n)==1)

{

m = n

memset(num,0,sizeof(num))

c = 0

while(n>0&&c<孙岁卖则逗21)

{

switch(n%3)

{

case 0:

n/=3

break

case 1:

num[c] = 1

n/=3

break

case 2:

num[c] = -1

n/=3

n++

break

case 3:

n/=3

n++

break

}

c++

}

if(c==21&&n!=0)

{

printf("No solution.\n")

}

else

{

bg = 1

printf("%lld =",m)

for(i=0i<21i++)

{

if(num[i]==1)

{

if(!bg) printf(" +")

printf(" 3^%d",i)

bg = 0

}

else if(num[i]==-1)

{

printf(" - 3^%d"雀宽,i)

bg = 0

}

}

printf("\n")

}

printf("\n")

}

}

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