直接上代码：
1 #include <cstdio>
2 #include <cstring>
3 #include <string>
4 #include <iostream>
5 #include <map>
6 #include <algorithm>
7 using namespace std;
8
9 map<string,int>mp_res;
10 map<string,int>mp_oper;
11 map<char,int>mp_dili;
12 string pre="";
13
14 int flag1=false,flag2=1;//flag1用作判断/*或*/是否在引号内，flag2判断内容是否处于注释状态
15 string mstr,flagstr,ansstr="";
16
17 string double_slash(string s)//双斜杠注释处理
18 {
19 string ans="";
20 bool flag=false;//判断//是否在双引号内作为字符串
21 for(int i=0;i<s.length();i++)
22 {
23 if(s[i]=='/'&&s[i+1]=='/'&&i+1<s.length()&&!flag)
24 break;
25 if(s[i]==34)
26 flag=!flag;
27 ans+=s[i];
28 }
29 return ans;
30 }
31
32 string block_comments(string s)//去除/* */的注释
33 {
34 string ans;
35 for(int i=0;i<s.length();i++)
36 {
37 if(s[i]==34)
38 flag1=!flag1;
39 if(s[i]=='/'&&s[i+1]=='*'&&i+1<s.length()&&!flag1)
40 {
41 flag2=0;
42 i+=2;
43 }
44 if(s[i]=='*'&&s[i+1]=='/'&&i+1<s.length()&&!flag1)
45 {
46 flag2=1;
47 i+=2;
48 }
49 if(flag2)
50 ans+=s[i];
51 }
52 return ans;
53 }
54
55 string space(string s)//多个连续空格并为一个，去除tab
56 {
57 bool flag=1;
58 string ans="";
59 for(int i=0;i<s.length();i++)
60 {
61 if(s[i]=='\t')
62 continue;
63 if(s[i]!=' ')
64 flag=0;
65 if(flag&&s[i]==' ')
66 continue;
67 if(s[i]==' ')
68 flag=1;
69 ans+=s[i];
70 }
71 return ans;
72 }
73
74 void init_table()//初始化对应值
75 {
76 string resword[35]={"int","long","short","float","double","char","bool","unsigned","signed","const","void","volatile",
77 "enum","struct","union","if","else","goto","switch","case","do","while","for","continue","break","return",
78 "default","typedef","auto","register","extern","static","sizeof","string","namespace"};
79 string operchar[33]={"+","-","*","/","%","++","--",
80 ">","<","==",">=","<=","!=",
81 "&&","||","!",
82 "&","|","~","^","<<",">>",
83 "=","+=","-=","*=","/=","&=","|=","^=",">>=","<<=","."};
84 char dilimiters[11]={'(',')','{','}','[',']',';','\'','"','#',','};
85 //标识符为1，数字为2
86 for(int i=0;i<35;i++)
87 mp_res[resword[i]]=i+2;
88 for(int i=0;i<33;i++)
89 mp_oper[operchar[i]]=i+37;
90 for(int i=0;i<11;i++)
91 mp_dili[dilimiters[i]]=i+70;
92 }
93
94 int is_digit(string s)//判断是否是数字
95 {
96 if(s[0]>='0'&&s[0]<='9')
97 {
98 for(int i=0;i<s.length();i++)
99 {
100 if(!(s[i]>='0'&&s[i]<='9'))
101 return -1;
102 }
103 return 1;
104 }
105 return 0;
106 }
107
108 void print()//处理输出
109 {
110 string temp="",oper="";
111 int x;
112 for(int i=0;i<ansstr.length();i++)
113 {
114 string ts=""; ts+=ansstr[i];
115 if(ansstr[i]!=' '&&mp_dili[ansstr[i]]==0&&mp_oper[ts]==0)
116 temp+=ansstr[i];
117 else
118 {
119 if(temp.size()>0)
120 {
121 cout<<temp;
122 x=30-temp.length();
123 for(int j=1;j<=x;j++)
124 printf(" ");
125 printf("|");
126 if(mp_res[temp]!=0)
127 {
128 printf("%10d",mp_res[temp]);
129 printf(" |");
130 printf(" keyword\n");
131 pre="keyword";
132 }
133 else if(is_digit(temp)==1)
134 {
135 printf("%10d",2);
136 printf(" |");
137 printf(" digit");
138 if(pre=="digit")
139 cout<<"(error)"<<endl;
140 else
141 cout<<endl;
142 pre="digit";
143 }
144 else if(is_digit(temp)==0)
145 {
146 printf("%10d",1);
147 printf(" |");
148 printf(" identifier");
149 if(pre=="identifier")
150 cout<<"(error)"<<endl;
151 else
152 cout<<endl;
153 pre="identifier";
154 }
155 else
156 {
157 printf("%10d",-1);
158 printf(" |");
159 printf(" ERROR\n");
160 }
161 temp="";
162
163 }
164 if(mp_dili[ansstr[i]]!=0)
165 {
166 cout<<ansstr[i];
167 for(int j=1;j<=29;j++)
168 printf(" ");
169 printf("|");
170 printf("%10d",mp_dili[ansstr[i]]);
171 printf(" |");
172 printf(" delimiter\n");
173 pre="delimiter";
174 }
175 if(mp_oper[ts]!=0)
176 {
177 while(mp_oper[ts]!=0)
178 {
179 oper=ts;
180 i++;
181 ts+=ansstr[i];
182 }
183 cout<<oper;
184 x=30-oper.length();
185 for(int j=1;j<=x;j++)
186 printf(" ");
187 printf("|");
188 printf("%10d",mp_oper[oper]);
189 oper="";
190 i--;
191 printf(" |");
192 printf(" operator\n");
193 pre="operator";
194 }
195
196 }
197
198 }
199 }
200
201 int main()
202 {
203 freopen("datain.txt","r",stdin);
204 freopen("dataout.txt","w+",stdout);
205 cout<<"单词符号 | 种别码 | 种类"<<endl;
206 while(getline(cin,mstr))//边读边去注释
207 {
208 mstr=double_slash(mstr);
209 ansstr+=block_comments(mstr);
210 ansstr+=' ';
211 }
212 ansstr=space(ansstr);//合并空格
213 init_table();
214 print();
215 }
来源：http://www.cnblogs.com/eastblue/p/8674249.html