中缀转后缀

  1 #include<stdio.h>
  2 #include<stdlib.h>
  3 #include<stdbool.h>
  4 #include<ctype.h>
  5 #define MAXOP 100
  6 typedef struct SNode{
  7     char *Data;
  8     int Top;
  9     int Maxsize;
 10 }Stack;
 11
 12 Stack *CreateStack(int Maxsize)
 13 {
 14     Stack *S;
 15     S=(Stack *)malloc(sizeof(struct SNode));
 16     S->Top=-1;
 17     S->Data=(char *)malloc(Maxsize * sizeof(char));
 18     S->Maxsize=Maxsize;
 19     return S;
 20 }
 21
 22 bool IsFull(Stack *S)
 23 {
 24     return (S->Top==S->Maxsize-1);
 25 }
 26
 27 void Push(Stack *S,char op)
 28 {
 29     if(!IsFull(S))
 30     {
 31         S->Data[++(S->Top)]=op;
 32     }
 33 }
 34
 35 bool IsEmpty(Stack *S)
 36 {
 37     return (S->Top==-1);
 38 }
 39
 40 char Pop(Stack *S)
 41 {
 42     char op;
 43     if (!IsEmpty(S))
 44     {
 45         op=S->Data[(S->Top)--];
 46     }
 47     return op;
 48 }
 49 char Top(Stack *S)
 50 {
 51     char op;
 52     if (!IsEmpty(S))
 53     {
 54         op=S->Data[(S->Top)];
 55     }
 56     return op;
 57 }
 58
 59 typedef enum {num,opr,end}Type;
 60
 61 Type GetOp(char *Expr,int *start,char *str)
 62 {
 63     int i=0;
 64     while ((str[0]=Expr[(*start)++])==‘ ‘);
 65     while (str[i]!=‘ ‘ && str[i]!=‘\0‘)
 66     {
 67         str[++i]=Expr[(*start)++];
 68     }
 69     if (str[i]==‘\0‘)(*start)--;
 70     str[i]=‘\0‘;
 71
 72     if (i==0) return end;
 73     else if (isdigit(str[0])||isdigit(str[1])) return num;
 74     else return opr;
 75 }
 76
 77 int Prior(char op)
 78 {
 79     switch (op)
 80     {
 81         case ‘*‘:
 82         case ‘/‘: return 2;
 83         case ‘+‘:
 84         case ‘-‘: return 1;
 85         case ‘(‘: return 0;
 86     }
 87 }
 88
 89 void PrintPostfixExp(char *Expr)
 90 {
 91     int start=0;
 92     Type T;
 93     char str[MAXOP];
 94     char op1,op2;
 95     Stack *S;
 96     S=CreateStack(MAXOP);
 97     while((T=GetOp(Expr,&start,str))!=end)
 98     {
 99         if (T==num)printf("%s ",str);
100         else
101         {
102             switch(str[0])
103             {
104                 case ‘(‘:Push(S,str[0]);break;
105                 case ‘)‘:
106                 {
107                     while(Top(S)!=‘(‘)printf("%c ",Pop(S));
108                     Pop(S);
109                     break;
110                 }
111                 case ‘+‘:
112                 case ‘-‘:
113                 case ‘*‘:
114                 case ‘/‘:
115                 {
116                     if (IsEmpty(S)){Push(S,str[0]);break;}
117                     else
118                     {
119                         op1=Top(S);
120                         if (Prior(str[0])<=Prior(op1))printf("%c ",Pop(S));
121                         Push(S,str[0]);
122                     }
123                     break;
124                 }
125
126             }
127         }
128     }
129     while(!IsEmpty(S))printf("%c ",Pop(S));
130 }
131
132 int main()
133 {
134     char Expr[MAXOP];
135     gets(Expr);
136     PrintPostfixExp(Expr);
137     return 0;
138 }