一個簡單的詞法分析程序

一個簡單的詞法分析程序，是關於C語言的，裏面的關鍵字可能不怎麼全面，某些不怎麼常用的符號可能也沒有，呵呵，不過它能把一些基本的關鍵字、運算符、分界符和空格識別出來，還能知道標識符和常量，功能很不全面，不過目前只能做到這個水平啦。希望能給初學編譯技術的朋友一些幫助。

#include <iostream> #define LEN 1000 struct KEYWORD { char name[10]; }keyword[33]={"main","coutinue","define","if","short","switch","volatile","do", "break","default","include","int","signed","typedef","while","case", "float","long","sizeof","union","char","double","for","register", "static","unsigned","const","else","goto","return","struct","void", "bool"}; using namespace std; bool IsKeyWord(string ch)//判斷字符是否爲關鍵字 { for(int j=0;j<33;j++) if(ch.compare(keyword[j].name)==0) return true; return false; } bool IsDigit(char ch)//判斷字符是否爲數字 { if(ch<='9'&&ch>='0') return true; return false; } bool IsChar(char ch)//判斷字符是否爲字母 { if((ch<='z'&&ch>='a')||(ch<='Z'&&ch>='A')) return true; return false; } bool IsBoundary(char ch)//判斷字符是否爲分界符 { char arr[12]={',',';','{','}','(',')','.','/"','/'','[',']',':'}; for (int j=0;j<12;j++) if(ch==arr[j]) return true; return false; } bool IsOperator(char ch) //判斷字符是否爲運算符 { if(ch=='='||ch=='+'||ch=='-'||ch=='*'||ch=='/') return true; return false; } bool IsSpace(char ch)//判斷是否爲空白符(空格、換行、製表符) { if(ch==' '||ch=='/n'||ch=='/t') return true; return false; } int main() { char ch[LEN]; char temp[10]; char nul[10]=" ";//9個空格 char bt[]="true"; char bf[]="false"; int i,j,I; i=j=I=0; for(j=0;j<10;j++) temp[j]=NULL; printf("***********************Let's try it**********************************/n"); printf("請輸入一行語句：/n"); gets(ch); for(i=0;i<strlen(ch);) { if(ch[i]==' '||ch[i]=='/n'||ch[i]=='/t') { printf("Get a blank/n"); i++; continue; } else if(IsChar(ch[i])) //判斷是否是字母 { while(IsChar(ch[i])||IsDigit(ch[i])) { temp[I]=ch[i]; I++; i++; } if(!strcmp(temp,bt)||!strcmp(temp,bf)) printf("%s/t/t布爾值/n",temp); else if(IsKeyWord(temp)) printf("%s/t/t關鍵字/n",temp); else printf("%s/t/t標識符/n",temp); for(j=0;j<10;j++) temp[j]=NULL; I=0; } else if(IsDigit(ch[i])) //判斷是否是數字 { while(IsDigit(ch[i])) { temp[I]=ch[i]; I++; i++; } printf("%s/t/t常數/n",temp); for(j=0;j<10;j++) temp[j]=NULL; I=0; } else if(IsBoundary(ch[i])) //判斷是否爲分界符 { temp[I]=ch[i]; i++; printf("%s/t/t分界符/n",temp); for(j=0;j<10;j++) temp[j]=NULL; I=0; } else if(IsOperator(ch[i])) //判斷是否是運算符 { temp[I]=ch[i]; i++; printf("%s/t/t運算符/n",temp); for(j=0;j<10;j++) temp[j]=NULL; I=0; } else //特殊符號 { temp[I]=ch[i]; i++; printf("%s/t/t特殊符號/n",temp); for(j=0;j<10;j++) temp[j]=NULL; I=0; } } printf("***********************We did it********************************/n"); return 0; }