后缀表达式

#include<stdio.h>
#define size 100
struct
{
    char ch;
    int pri;
}
lpri[]={{'=',0},{'(',1},{'*',5},{'/',5},{'+',3},{'-',3},{')',6}},
rpri[]={{'=',0},{'(',6},{'*',4},{'/',4},{'+',2},{'-',2},{')',1}};
int leftpri(char op)
{
    int i;
    for(i=0;i<7;i++)
        if(lpri[i].ch==op)
            return lpri[i].pri;
}
int rightpri(char op)
{
    int i;
    for(i=0;i<7;i++)
        if(rpri[i].ch==op)
            return rpri[i].pri;
}
int inop(char ch)
{
    if(ch=='('||ch=='*'||ch=='/'||ch=='+'||ch=='-'||ch==')')
        return 1;
    else
        return 0;
}
int precede(char op1,char op2)
{
    if(leftpri(op1)==rightpri(op2))
        return 0;
    else if(leftpri(op1)<rightpri(op2))
        return -1;
    else
        return 1;
}
void trans(char *exp,char postexp[])
{
    int i=0;
    struct
    {  
        char data[size];
        int top;
    }op;
    op.top=-1;
    op.top++;
    op.data[op.top]='=';
    while(*exp!='\0')
    {
        if(!inop(*exp))
        {
            while(*exp>='0'&&*exp<='9')
            {
                postexp[i++]=*exp;
                    exp++;
            }
            postexp[i++]='#';
        }
        else
            switch(precede(op.data[op.top],*exp))
        {
    case -1:
        op. top++;
        op.data[op.top]=*exp;
        exp++;
        break;
    case 0:
        op.top--;
        exp++;
        break;
    case 1:
        postexp[i++]=op.data[op.top];
        op.top--;
        break;
        }
    }
    while(op.data[op.top]!='=')
    {
        postexp[i++]=op.data[op.top];
        op.top--;
    }
    postexp[i]='\0';
}

#include<stdio.h>
#include<string.h>
#define maxsize 100
#define maxop 7
extern int leftpri(char op);        //求运算符op的优先级
extern int rightpri(char op);
extern int inop(char ch);        //判断ch是否为运算符
extern void trans(char *exp,char postexp[]);    //将算术表达式exp转换成后缀表达式postexp
void main()
{
    char exp[maxsize],postexp[maxsize];
    scanf("%s",exp);
    trans(exp,postexp);
    printf("\n%s\n",exp);
    printf("\n%s\n",postexp);
}