设计一个程序，演示用算符优先法对算术表达式求值的过程

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#define STACK_INIT_SIZE 100
#define STACKINCREMENT 10
typedef struct{
 int *base;
 int *top;
 int stacksize;
}SqStack;
void InitStack(SqStack *s)
{
 s->base=(int *)malloc(STACK_INIT_SIZE *sizeof(int));
 if(!s->base) exit(1);
 s->top=s->base;
 s->stacksize=STACK_INIT_SIZE;
}
void GetTop(SqStack *s,int *e)
{
 if(s->top==s->base)
 {
    printf("ERROR!\n");
    exit(1);
 }
 *e=*(s->top-1);
}
void Push(SqStack *s,int e)
{
 if(s->top-s->base>=s->stacksize)
 {

    s->base=(int *)realloc(s->base,(s->stacksize+STACKINCREMENT*sizeof(int)));
    if(!s->base)
    {
     printf("overflow!");
     exit(1);
    }
    s->top=s->base+s->stacksize;
    s->stacksize+=STACKINCREMENT;
 }
 *s->top++=e;
}
void Pop(SqStack *s,int *e)
{
 if(s->top==s->base)
    exit(1);
 *e=*--s->top;
}
int precede(int Top_char,int s1_char)
{
 int i,pre[2],op[2];
 op[0]=Top_char;
 op[1]=s1_char;
 for(i=0;i<2;i++)
    switch(op[i])
 {
    case'(': case')': pre[i]=0;break;
    case'+': case'-': pre[i]=1;break;
    case'*': case'/': pre[i]=2;break;
    case'^': pre[i]=3;break;
 }