编译原理词法分析程序-白红宇

编译原理词法分析程序

阅读量：5246 次

发布时间：2019-06-14

本文共 1132 字，大约阅读时间需要 3 分钟。

#include 
    
     #include
     
      #include
      
       #include
       
        #include
        
         using namespace std;#define  MAX 22char ch =' ';string key[15]={"switch","break","if","then","else","while","write","read","do", "int","const","char","float","double","for"};int Iskey(string c)    //关键字判断{   int i;   for(i=0;i
         
          ='a'))||((c<='Z')&&(c>='A'))) return 1; else return 0;}int IsDigit(char c) //判断是否为数字{ if(c>='0'&&c<='9') return 1; else return 0;}void analyse(FILE *fpin) //词法分析程序{ string arr=""; while((ch=fgetc(fpin))!=EOF) { arr=""; if(ch==' '||ch=='\t'||ch=='\n') { } else if(IsLetter(ch)) { while(IsLetter(ch)||IsDigit(ch)) { if((ch<='Z')&&(ch>='A')) ch=ch+32; arr=arr+ch; ch=fgetc(fpin); } fseek(fpin,-1L,SEEK_CUR); if (Iskey(arr)) { cout<
          
           <<"\t$关键字"<
           
            ' :{ch=fgetc(fpin); if(ch=='=') cout<<">="<<"\t$运算符"<
            
             ')cout<<">>"<<"\t$输入控制符"<
             
              "<<"\t$运算符"<
              
               ') cout<<"<>"<<"\t$运算符"<
               
                >in_fn; if((fpin=fopen(in_fn,"r"))!=NULL) break; else cout<<"文件路径错误！请输入源文件名（包括路径和后缀名）:"; } cout<<"\n********************分析如下*********************"<