设计将中缀表达式转换为后缀表达式的算法

设计将中缀表达式转换为后缀表达式的算法整代码如下：
#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#include"Stack.h"
#define MAX 30
int Precedence(char ch)
{
if(ch=='+'||ch=='-')return 2;
else if(ch=='*'||ch=='/')return 3;
else if(ch=='('||ch==')')return 4;
else if(ch=='@')return 1;
else return 0;
}
void Change(char *s1,char *s2)
{
Stack S=NewEmpty(MAX);
int i=0,j=0,one=0;
char ch=s1[i];
Push('@',S);
while(ch!='@')
{
if(ch==' ')
ch=s1[++i];
else if(isalnum(ch)!=0)
{
if(one==1)
{
s2[j++]=' ';
}
s2[j++]=ch;
ch=s1[++i];
one=0;
}
else if(ch=='(')
{
Push(ch,S);
ch=s1[++i];
one=1;
}
else if(ch==')')
{
while(Peek(S)!='(')
s2[j++]=Pop(S);
Pop(S);
ch=s1[++i];
one=1;
}
else if(ch=='+'||ch=='-'||ch=='*'||ch=='/')
{
while(Peek(S)!='('&&Precedence(Peek(S))>=Precedence(ch)) {
s2[j++]=Pop(S);
one=1;
}
Push(ch,S);
ch=s1[++i];
one=1;
}
}
while(StackEmpty(S)!=1)
{
s2[j++]=Pop(S);
one=1;
}
s2[j]='\0';
}
int main()
{
char s1[MAX],s2[MAX];
printf("Enter the equation:\n");
gets(s1);
Change(s1,s2);
printf("%s\n",s2);
return 0;
}
其中：Stack.h如下：
#ifndef STACK_H
#define STACK_H
#include<stdio.h>
#include<stdlib.h> typedefstructastack *Stack; typedefstructastack
{
int top;
intmaxtop;
char* data;
}Astack;
Stack NewEmpty(int size)
{
Stack S=(Stack)malloc(sizeof(Astack)); S->maxtop=size;
S->top=-1;
S->data=(char*)malloc(size*sizeof(char)); return S;
}
intStackEmpty(Stack S)
{
return S->top<0;
}
intStackFull(Stack S)
{
return S->top==S->maxtop;
}
int Peek(Stack S)
{
return S->data[S->top];
}
void Push(char x,Stack S)
{
if(StackFull(S))
{
printf("Stack is full!\n");
exit(1);
}
else
S->data[++S->top]=x;
}
int Pop(Stack S)
{
if(StackEmpty(S))
{
printf("Stack is empty!\n");
exit(1);
}
else
return S->data[S->top--];
}
Stack NewStack(int size)
{
Stack S=NewEmpty(size);
inti,x,num;
printf("Please enter the number of data:\n"); scanf("%d",&num);
for(i=0;i<num;i++)
{
printf("Please enter the %d date:\n",i+1); scanf("%c",&x);
Push(x,S);
}
return S;
}
void ShowStack(Stack S)
{
int i;
for(i=0;i<=S->top;i++) {
printf(" %c",S->data[i]); }
printf("\n");
}
#endif。