[栈和队列]从中缀向后缀转换表达式

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #define INIT_STACK_SIZE 100
 5 typedef struct
 6 {
 7     char * chOperator;
 8     int dwtop;
 9 }OPND;
10 
11 void InitStack(OPND *);
12 char Pop(OPND *);
13 void Push(OPND *,char );
14 char GetTop(OPND);
15 
16 char ComparePri(char op1,char op2);
17 void printStack(OPND);
18 
19 char stringBuffer[128] = {‘\0‘};
20 char stringValue[128] = {‘\0‘};
21 int main()
22 {
23     OPND opnd;
24     int N = 0;
25     char ch ,*strValue,*strBuffer;
26     scanf("%d",&N);
27     getchar();
28     while(N--){
29 
30         strValue = stringValue;
31         strBuffer = stringBuffer;
32 
33         memset(stringValue,0,128*sizeof(char));
34         memset(stringBuffer,0,128*sizeof(char));
35 
36         gets(stringBuffer);
37         InitStack(&opnd);
38         Push(&opnd,‘#‘);
39 
40         ch = *strBuffer++;
41         while(ch != ‘#‘ || GetTop(opnd) != ‘#‘){
42             if((ch >= ‘a‘ && ch <= ‘z‘)||(ch >= ‘A‘ && ch <= ‘Z‘)) {
43                 *strValue = ch;
44                 strValue++;
45                 ch = *(strBuffer++);
46             }
47             else
48             switch(ComparePri(GetTop(opnd),ch)){
49                 case ‘<‘ : Push(&opnd,ch); ch = *(strBuffer++); break;
50                 case ‘=‘ : Pop(&opnd);     ch = *(strBuffer++); break;
51                 case ‘>‘ : *strValue = Pop(&opnd); strValue++; break;
52             }
53         }
54         puts(stringValue);
55     }
56     return 0;
57 }
58 void InitStack(OPND *S)
59 {
60     S->chOperator = (char *)malloc(INIT_STACK_SIZE * sizeof(char));
61     if(!S->chOperator) exit(1);
62     S->dwtop = 0;
63 }
64 void Push(OPND *S,char ch)
65 {
66     *(S->chOperator + S->dwtop) = ch;
67     S->dwtop++;
68 }
69 char Pop(OPND *S)
70 {
71     S->dwtop--;
72     return *(S->chOperator + S->dwtop);
73 }
74 char ComparePri(char op1,char op2)
75 {
76     if((op1 == ‘+‘ || op1 == ‘-‘)&&(op2 == ‘*‘ || op2 == ‘/‘))        return ‘<‘;
77     else if((op1 == ‘(‘ && op2 == ‘)‘)||(op1 == ‘#‘ && op2 == ‘#‘)) return ‘=‘;
78     else if(op1 == ‘(‘ || op1 == ‘#‘ || op2 == ‘(‘)                 return ‘<‘;
79     else return ‘>‘;
80 }
81 void printStack(OPND opnd)
82 {
83     while(opnd.dwtop){
84         opnd.dwtop--;
85         printf("%c",*(opnd.chOperator + opnd.dwtop));
86     }
87 }
88 char GetTop(OPND opnd)
89 {
90     return *(opnd.chOperator + opnd.dwtop -1);
91 }