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ID:5594705
大小:27.00 KB
页数:4页
时间:2017-12-19
《大学作业-词法分析器》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、大学作业-词法分析器#include#includeusingnamespacestd;#defineMAX22charch='';stringkey[15]={"begin","end","if","then","else","while","write","read","do","call","const","char","until","procedure","repeat"};intIskey(stringc)//关键字判断{inti;for(i=0;i2、return1;return0;}intIsLetter(charc)//判断是否为字母{if(((c<='z')&&(c>='a'))3、4、((c<='Z')&&(c>='A')))return1;elsereturn0;}intIsDigit(charc)//判断是否为数字{if(c>='0'&&c<='9')return1;elsereturn0;}voidanalyse(FILE*fpin){stringarr="";while((ch=fgetc(fpin))!=EOF){arr="";if(ch==''5、6、ch=='t'7、8、ch==''){}el9、seif(IsLetter(ch)){while(IsLetter(ch)10、11、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<<"(关键字,"<12、13、ch=='.'&&IsDigit(fgetc(fpin14、))){arr=arr+ch;ch=fgetc(fpin);}fseek(fpin,-1L,SEEK_CUR);cout<<"(常数,"<15、"=="<<",EQ)"<':{ch=fgetc(fpin);if(ch=='=')cout<<"("<<">="<<",LB)"<"<<",-)"<16、se{cout<<"("<<"<"<<",-)"<>in_fn;if((fpin=fopen(in_fn,"r"))!=NULL)break;elsecout<<"输入有误,请重新输入:";}cout<<"分析如下:"<17、out<>a;}
2、return1;return0;}intIsLetter(charc)//判断是否为字母{if(((c<='z')&&(c>='a'))
3、
4、((c<='Z')&&(c>='A')))return1;elsereturn0;}intIsDigit(charc)//判断是否为数字{if(c>='0'&&c<='9')return1;elsereturn0;}voidanalyse(FILE*fpin){stringarr="";while((ch=fgetc(fpin))!=EOF){arr="";if(ch==''
5、
6、ch=='t'
7、
8、ch==''){}el
9、seif(IsLetter(ch)){while(IsLetter(ch)
10、
11、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<<"(关键字,"<12、13、ch=='.'&&IsDigit(fgetc(fpin14、))){arr=arr+ch;ch=fgetc(fpin);}fseek(fpin,-1L,SEEK_CUR);cout<<"(常数,"<15、"=="<<",EQ)"<':{ch=fgetc(fpin);if(ch=='=')cout<<"("<<">="<<",LB)"<"<<",-)"<16、se{cout<<"("<<"<"<<",-)"<>in_fn;if((fpin=fopen(in_fn,"r"))!=NULL)break;elsecout<<"输入有误,请重新输入:";}cout<<"分析如下:"<17、out<>a;}
12、
13、ch=='.'&&IsDigit(fgetc(fpin
14、))){arr=arr+ch;ch=fgetc(fpin);}fseek(fpin,-1L,SEEK_CUR);cout<<"(常数,"<15、"=="<<",EQ)"<':{ch=fgetc(fpin);if(ch=='=')cout<<"("<<">="<<",LB)"<"<<",-)"<16、se{cout<<"("<<"<"<<",-)"<>in_fn;if((fpin=fopen(in_fn,"r"))!=NULL)break;elsecout<<"输入有误,请重新输入:";}cout<<"分析如下:"<17、out<>a;}
15、"=="<<",EQ)"<':{ch=fgetc(fpin);if(ch=='=')cout<<"("<<">="<<",LB)"<"<<",-)"<16、se{cout<<"("<<"<"<<",-)"<>in_fn;if((fpin=fopen(in_fn,"r"))!=NULL)break;elsecout<<"输入有误,请重新输入:";}cout<<"分析如下:"<17、out<>a;}
16、se{cout<<"("<<"<"<<",-)"<>in_fn;if((fpin=fopen(in_fn,"r"))!=NULL)break;elsecout<<"输入有误,请重新输入:";}cout<<"分析如下:"<17、out<>a;}
17、out<>a;}
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