词法分析器文档分解.docx

词法分析器文档分解.docx

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词法分析器文档分解

词法分析程序文档

说明：

该词法分析器实现对C语言源代码进行词法分析的功能，由文件输入，将输入的源代码输出为token序列，用二元组形式由文件和屏幕输出，文件输出首先输入源文件路径和文件名称，将注释过滤，能够报告不合法字符，并且记录源代码的行数，单词数（包括关键字，标识符和常量）和字符数（包括字母，数字，标点符号，运算符，空格和换行符）。

程序设计：

具体见源代码

源代码：

#include

#include

#include

#include

usingnamespacestd;

#defineMAX32

charch='';

intline=1,zifu=1,word=0;

/*line记录行数

zifu记录字符数（包括字母，数字，标点符号，运算符，空格和换行符）

word记录单词数（包括关键字，标识符和常量）*/

stringkey[32]={"auto","break","case","char","const","continue","default","do","double",

"else","enum","extern","float","for","goto","if","int","long","register",

"return","short","signed","sizeof","static","struct","switch","typedef",

"union","unsigned","void","volatile","while"

};//c语言中的所有关键字

intIskey（stringc）//关键字判断

{

inti;

for（i=0;i

{

if（key[i].compare（c）==0）{//将字符串与关键字一一进行比较

return1;

}

}

return0;

}

intIsLetter（charc）//判断是否为字母

{

if（（（c<='z'）&&（c>='a'））||（（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,FILE*fpout）

{

stringarr="";

stringstr="";

while（（ch=fgetc（fpin））!

=EOF）

{zifu++;//将文件中的字符逐一进行扫描，包括字母，数字，标点符号，运算符，空格和换行符

arr="";

if（IsLetter（ch））//对开头是字母或数字的字符串进行判断

{

while（IsLetter（ch）||IsDigit（ch）||ch=='_'）//符合标识符或者关键字标准的字符串进行判断

{

if（（ch<='Z'）&&（ch>='A'））ch=ch+32;

arr=arr+ch;//将每个单个读取的字符连成字符串

ch=fgetc（fpin）;

}

fseek（fpin,-1L,SEEK_CUR）;//不满足条件的多读取的字符回退一格

if（Iskey（arr））//判断字符串是否是关键字

{

fprintf（fpout,"（%s%s）\n",arr.c_str（）,"key"）;

printf（"（%s%s）\n",arr.c_str（）,"key"）;

word++;

}

else//字符串不是关键字则判定为标识符

{

fprintf（fpout,"（%s%s）\n",arr.c_str（）,"id"）;

printf（"（%s%s）\n",arr.c_str（）,"id"）;

word++;

}

}

elseif（IsDigit（ch））//开头为数字的串即为常量

{

while（IsDigit（ch）||ch=='.'&&IsDigit（fgetc（fpin）））

{

arr=arr+ch;

ch=fgetc（fpin）;

}

fseek（fpin,-1L,SEEK_CUR）;

fprintf（fpout,"（%s%s）\n",arr.c_str（）,"num"）;

printf（"（%s%s）\n",arr.c_str（）,"num"）;

word++;

}

elseswitch（ch）//既不是数字也不是字母的符号判定

{

case'+':

{

ch=fgetc（fpin）;//判定++，+=，+

if（ch=='+'）

{

fprintf（fpout,"（%s%s）\n","++","-"）;

printf（"（%s%s）\n","++","-"）;

zifu++;

}

if（ch=='='）

{

fprintf（fpout,"（%s%s）\n","+=","-"）;

printf（"（%s%s）\n","+=","-"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n","+","-"）;

printf（"（%s%s）\n","+","-"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'-':

{

ch=fgetc（fpin）;

if（ch=='-'）//判定--，-=，-

{

fprintf（fpout,"（%s%s）\n","--","-"）;

printf（"（%s%s）\n","--","-"）;

zifu++;

}

if（ch=='='）

{

fprintf（fpout,"（%s%s）\n","-=","-"）;

printf（"（%s%s）\n","-=","-"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n","-","-"）;

printf（"（%s%s）\n","-","-"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'*':

fprintf（fpout,"（%s%s）\n","*","-"）;

printf（"（%s%s）\n","*","-"）;

break;

case'=':

{

ch=fgetc（fpin）;//判定==，=

if（ch=='='）{

fprintf（fpout,"（%s%s）\n","==","-"）;

printf（"（%s%s）\n","==","-"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n","=","EQ"）;

printf（"（%s%s）\n","=","EQ"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'/':

{

ch=fgetc（fpin）;//判定是注释还是运算符/

if（ch=='*'）//形如/**/的注释，将注释过滤

{zifu--;

ch=fgetc（fpin）;

while（（ch!

='*'）&&（ch=fgetc（fpin））=='/'）

;

}

elseif（ch=='/'）//形如//的注释，将注释过滤

{zifu--;

ch=fgetc（fpin）;

while（ch!

='\n'）ch=fgetc（fpin）;

line++;

}

else

{

fprintf（fpout,"（%s%s）\n","/","-"）;

printf（"（%s%s）\n","/","-"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'%':

fprintf（fpout,"（%s%s）\n","%","-"）;

printf（"（%s%s）\n","%","-"）;

break;

case'#':

fprintf（fpout,"（%s%s）\n","#","-"）;

printf（"（%s%s）\n","#","-"）;

break;

case'!

':

{

ch=fgetc（fpin）;//判定！

=还是！

if（ch=='='）

{

fprintf（fpout,"（%s%s）\n","!

=","-"）;

printf（"（%s%s）\n","!

=","-"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n","!

","-"）;

printf（"（%s%s）\n","!

","-"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'|':

{

ch=fgetc（fpin）;

if（ch=='|'）//判定||还是|

{

fprintf（fpout,"（%s%s）\n","||","-"）;

printf（"（%s%s）\n","||","-"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n","|","-"）;

printf（"（%s%s）\n","|","-"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'&':

{

ch=fgetc（fpin）;

if（ch=='&'）//判定&&还是&

{

fprintf（fpout,"（%s%s）\n","&&","-"）;

printf（"（%s%s）\n","&&","-"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n","&","-"）;

printf（"（%s%s）\n","&","-"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'（':

fprintf（fpout,"（%s%s）\n","（","-"）;

printf（"（%s%s）\n","（","-"）;

break;

case'）':

fprintf（fpout,"（%s%s）\n","）","-"）;

printf（"（%s%s）\n","）","-"）;

break;

case'[':

fprintf（fpout,"（%s%s）\n","[","-"）;

printf（"（%s%s）\n","[","-"）;

break;

case']':

fprintf（fpout,"（%s%s）\n","]","-"）;

printf（"（%s%s）\n","]","-"）;

break;

case';':

fprintf（fpout,"（%s%s）\n",";","-"）;

printf（"（%s%s）\n",";","-"）;

break;

case'.':

fprintf（fpout,"（%s%s）\n",".","-"）;

printf（"（%s%s）\n",".","-"）;

break;

case',':

fprintf（fpout,"（%s%s）\n",",","-"）;

printf（"（%s%s）\n",",","-"）;

break;

case'{':

fprintf（fpout,"（%s%s）\n","{","-"）;

printf（"（%s%s）\n","{","-"）;

break;

case'}':

fprintf（fpout,"（%s%s）\n","}","-"）;

printf（"（%s%s）\n","}","-"）;

break;

case'"':

fprintf（fpout,"（%s%s）\n","引号","-"）;

printf（"（%s%s）\n","引号","-"）;

break;

case'?

':

fprintf（fpout,"（%s%s）\n","?

","-"）;

printf（"（%s%s）\n","?

","-"）;

break;

case':

':

fprintf（fpout,"（%s%s）\n",":

","-"）;

printf（"（%s%s）\n",":

","-"）;

break;

case'>':

{

ch=fgetc（fpin）;

if（ch=='='）//判定>=还是>

{

fprintf（fpout,"（%s%s）\n",">=","GE"）;

printf（"（%s%s）\n",">=","GE"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n",">","GT"）;

printf（"（%s%s）\n",">","GT"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'<':

{

ch=fgetc（fpin）;//判定<=还是<还是<>

if（ch=='='）{

fprintf（fpout,"（%s%s）\n","<=","LE"）;

printf（"（%s%s）\n","<=","LE"）;

zifu++;

}

elseif（ch=='>'）{

fprintf（fpout,"（%s%s）\n","<>","NE"）;

printf（"（%s%s）\n","<>","NE"）;

zifu++;

}

else

{

fprintf（fpout,"（%s%s）\n","<","LT"）;

printf（"（%s%s）\n","<","LT"）;

fseek（fpin,-1L,SEEK_CUR）;

}

}

break;

case'':

break;

case'\n':

line++;//每读到\n，记录行数

break;

default:

fprintf（fpout,"（%c%s）\n",ch,"不合法"）;

printf（"（%c%s）\n",ch,"不合法"）;

break;

}

}

}

intmain（）

{

charin_fn[30];

FILE*fpin,*fpout;

fpout=fopen（"playover.txt","w"）;

cout<<"请输入源文件名（包括路径和后缀名）:

";

for（;;）

{

cin>>in_fn;

if（（fpin=fopen（in_fn,"r"））!

=NULL）break;

elsecout<<"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"<

analyse（fpin,fpout）;

cout<<"行数:

"<

cout<<"单词数:

"<

cout<<"字符数:

"<

fclose（fpout）;

fclose（fpin）;

system（"pause"）;

return0;

}

输入文件：

输出文件：