栈的应用之中缀表达式转化为后缀表达式(逆波兰表达式)

Posted 2020-06-17

  1 #include<stdio.h>
  2 #include<stdlib.h>
  3 
  4 #define OK         1
  5 #define ERROR         0
  6 #define STACK_INIT_SIZE 20
  7 #define STACK_INCREMENT 10
  8 
  9 typedef char Elemtype;
 10 typedef int Status;
 11 
 12 typedef struct StackNode{
 13     Elemtype* base;
 14     Elemtype* top;
 15     int stackSize;
 16 }StackNode;
 17 typedef struct StackNode* Stack;
 18 
 19 Status InitStack(Stack s){
 20     s->base = (Elemtype*)malloc(sizeof(Elemtype) * STACK_INCREMENT);
 21     if(! s->base){
 22         return ERROR;
 23     }
 24     s->top = s->base;
 25     s->stackSize = STACK_INIT_SIZE;
 26     return OK;
 27 }
 28 Status Pop(Stack s,Elemtype* value){
 29     if(s->base == s->top){
 30         printf("pop ERROR\n");
 31         return ERROR;
 32     }
 33     *value = *(--(s->top));
 34     return OK;
 35 }
 36 Status Push(Stack s, Elemtype value){
 37     if(s->top - s->base == s->stackSize){
 38         s->base = (Elemtype*)realloc(s->base,sizeof(Elemtype) * (STACK_INIT_SIZE + STACK_INCREMENT));
 39         if(! s->base)
 40             return ERROR;
 41         s->top = s->base + STACK_INIT_SIZE;
 42         s->stackSize = STACK_INCREMENT + STACK_INIT_SIZE;
 43     }
 44     *(s->top) = value;
 45     s->top++;
 46     return OK;
 47 }
 48 int StackLength(Stack s){
 49     return s->top - s->base;
 50 } 
 51 //test
 52 Status ShowStack(Stack s){
 53     while(s->top != s->base){
 54         printf("%c  ",*(--(s->top)));
 55     }
 56     printf("\n");
 57 }
 58 
 59 Status Infix2Postfix(){            //将中缀表达式转化为后缀表达式
 60     StackNode s;
 61     InitStack(&s);
 62     char c;
 63     char c1;
 64     printf("  Please Enter Infix expression\n");
 65     printf("  -------note: number separeted by space,end of ‘#‘\n\n");
 66     scanf("%c", &c);
 67     /* Note:如果是数字：    直接输出控制台；
 68      *      如果是*，/，（: 直接Push
 69      *      如果是+，-：    则要将*,/,+,-都进行Pop，直到stack为空或者是遇到了‘(‘
 70      *      如果是‘)‘：     将在遇到‘(‘之前的所有的都要Pop
 71      * */
 72     while(‘#‘ != c){
 73         while(c >= ‘0‘ && c <= ‘9‘){     //如果是数字，则直接输出
 74             printf("%c", c);
 75             scanf("%c", &c);
 76             if( c < ‘0‘ || c > ‘9‘){
 77                 printf("%c", ‘ ‘);
 78                 break;
 79             }
 80         }
 81         if(‘+‘ == c || ‘-‘ == c){    //如果是 + 或者是 -
 82             if(!StackLength(&s)){        //如果stack为空的话，直接Push
 83                 Push(&s,c);
 84             }
 85             else{            //不为空的话需要Pop进行比较/+-*都需要Pop
 86                 Pop(&s,&c1);
 87                 while( ‘(‘ != c1 ){
 88                     printf("%c ", c1);
 89                     if(StackLength(&s) == 0){
 90                         break;
 91                     }
 92                     else
 93                         Pop(&s, &c1);
 94                 }
 95                 if( ‘(‘ == c1 )
 96                     Push(&s, c1);
 97                 Push(&s, c);
 98             }
 99         }
100         else if(‘*‘ == c || ‘/‘ == c || ‘(‘ == c){    //如果是*或者是/
101             Push(&s, c);
102         }
103         else if( ‘)‘ == c ){
104             Pop(&s,&c1);
105             while( ‘(‘ != c1){
106                 printf("%c ", c1);
107                 Pop(&s, &c1);
108             }
109         }
110         else if( ‘#‘ == c ){
111             break;
112         }
113         else{
114             printf("Input Is ERROR!\n");
115             return ERROR;
116         }
117         scanf("%c", &c);
118     }
119 
120     while(StackLength(&s)){
121         Pop(&s,&c1);
122         printf("%c ", c1);
123     }
124     return OK;
125 }
126 int main(){
127     Infix2Postfix();
128 /*
129     Stack s;
130     InitStack(s);
131     Push(s,‘a‘);
132     Push(s,‘r‘);
133     Push(s,‘e‘);
134     Push(s,‘d‘);
135     ShowStack(s);
136 */
137     return 0;
138 }