词法分析程序设计

 1 #include <iostream>
 2 #include <cstring>
 3 using namespace std;
 4 
 5 struct { int number; string str[10]; } keywords={3,"int","main","return"} ;         //关键词 
 6 struct { int number; string str[10]; } operators ={5,"+","*","=","+=","*="};        //运算符 
 7 struct { int number; string str[10]; } boundaries ={6,"(",")","{","}",",",";"} ;    //分界符 
 8 struct { int number; string str[100];} identifieres={0};                            //标识符 
 9 struct { int number; string str[100];} Unsigned_integer={0};                        //无符号整数 
10 
11 char k=0;
12 string st=""; 
13 int main(){
14     int i;    char ch;  bool nochar=1;     
15     
16     do{
17         if(nochar)cin.get(ch);
18         if(ch==‘(‘){st+="<3,0>";nochar=1;} 
19         else if(ch==‘)‘){ st+="<3,1>";nochar=1; }    
20         else if(ch==‘{‘){ st+="<3,2>";nochar=1; }  
21         else if(ch==‘}‘){ st+="<3,3>";nochar=1; }    
22         else if(ch==‘,‘){ st+="<3,4>";nochar=1; }    
23         else if(ch==‘;‘){ st+="<3,5>";nochar=1; }      
24         else if(ch==‘+‘){
25             cin.get(ch); 
26             if(ch==‘=‘){    
27                 st+="<2,3>";nochar=1;  
28             } 
29             else{
30                 st+="<2,0>";nochar=1;     
31             } 
32         }
33         else if(ch==‘*‘){
34             cin.get(ch); 
35             if(ch==‘=‘){
36                 st+="<2,4>";nochar=1;
37             } 
38             else{
39                 st+="<2,1>";nochar=1;     
40             } 
41         }
42         else if(ch==‘=‘){
43             st+="<2,2>";nochar=1;      
44         }
45         else if(‘0‘<=ch&&ch<=‘9‘){
46             string nstring=""; nochar=0;
47             do{
48                 nstring+=ch;
49                 cin.get(ch); 
50             } while(‘0‘<=ch&&ch<=‘9‘);
51             for(k=0;k<Unsigned_integer.number&&Unsigned_integer.str[k]!=nstring;k++ );
52     
53             if(k==Unsigned_integer.number ){
54                 Unsigned_integer.str[k] = nstring;
55                 st+="<5,";st+=char(‘0‘+k); st+=">";
56                 Unsigned_integer.number++;  
57             }
58             else{ 
59                 st+="<5,";st+=char(‘0‘+k);st+=">";   
60             }
61         }
62         else if(‘a‘<=ch&&ch<=‘z‘||‘A‘<=ch&&ch<=‘Z‘){ 
63             string nstring="";nochar=0;
64             do{
65                 nstring+=ch;
66                 cin.get(ch);
67             } while(‘a‘<=ch&&ch<=‘z‘||‘A‘<=ch&&ch<=‘Z‘) ;  //读入关键字或者标示符的东西 
68             
69             for(k=0;k<= keywords.number &&keywords.str[k]!=nstring;k++ );               
70             if(k<keywords.number ){
71                 //测得输入字符是关键字之一 
72                 st+="<1,";   st+=char(‘0‘+k);st+=">";   
73             }                  
74             else{
75                 //测得输入字符不是关键字之一，而是标识符   
76                 for(k=0;k<identifieres.number && identifieres.str[k]!=nstring;k++ );    //检查是否是已经记录过的标识符 
77                 if(k==identifieres.number ){                //不是已经标识过的标识符 
78                     identifieres.str[k]=nstring;
79                     st+="<4,";st=st+char(‘0‘+k);st+=">";   
80                     identifieres.number++;  
81                 }
82                 else{
83                     st+="<4,";st=st+char(‘0‘+k);st+=">"; 
84                 }
85             }
86         }
87         else nochar=1;  
88        
89     } while(ch!=‘#‘);
90     
91     cout<<st<<endl;
92     cout<<"identifieres:";
93         for(i=0;i<identifieres.number;i++ ){cout<<identifieres.str[i]<<" ";}    cout<<endl;
94     cout<<"Unsigned_integer:"; 
95         for(i=0;i<Unsigned_integer.number;i++ ){cout<<Unsigned_integer.str[i]<<" ";}   cout<<endl;
96     
97     return 0;    
98 }               
99