编译原理词法分析程序.doc

#include #include #include #include #include using namespace std;ifstream fp(source.txt,ios:in);char cbuffer;char *key13=if,else,for,while,do,return,break,continue,int,void,main,const,printf; /关键字char *border7= , , ; , , , ( , ) ,/; /分界符char *arithmetic6=+ , - , * , / , + , -; /运算符char *relation7= , , = , = ,!=; /关系运算符 char *lableconst80; /标识符int constnum=40;int lableconstnum=0; int linenum=1; /统计常数和标识符数量 int search(char searchchar,int wordtype) int i=0,t=0; switch (wordtype) case 1: for (i=0;i=12;i+) /关键字 if (strcmp(keyi,searchchar)=0) return(i+1); return(0); case 2: for (i=0;i=6;i+) /分界符 if (strcmp(borderi,searchchar)=0) return(i+1); return(0); case 3: for (i=0;i=5;i+) /运算符 if (strcmp(arithmetici,searchchar)=0) return(i+1); return(0); case 4: for (i=0;i=6;i+) /关系运算符 if (strcmp(relationi,searchchar)=0) return(i+1); return(0); case 5: for (t=40;t=constnum;t+) /常数 if (strcmp(searchchar,lableconstt)=0)/判断该常数是否已出现过 return(t+1); lableconstt-1=(char *)malloc(sizeof(searchchar);/为新的元素分配内存空间 strcpy(lableconstt-1,searchchar);/为数组赋值lableconst指针数组名 constnum+; /常数个数自加 return(t); case 6: for (i=0;i=lableconstnum;i+) if (strcmp(searchchar,lableconsti)=0) /判断标识符是否已出现过 return(i+1); lableconsti-1=(char *)malloc(sizeof(searchchar); strcpy(lableconsti-1,searchchar); lableconstnum+; /标识符个数自加 return(i); default:cout错误！; char alphaprocess(char buffer) /字符处理过程 int atype; int i=-1; char alphatp20; while (isalpha(buffer)|(isdigit(buffer) /这两个函数分别是判字符和判数字函数位于ctype.h中 alphatp+i=buffer; fp.get(buffer); alphatpi+1=0;/在末尾添加字符串结束标志 if (atype=search(alphatp,1) coutlinenum: linenum String= alphatpttt关键字endl; else atype=search(alphatp,6); /标识符 coutlinenum: linenum String= alphatpttt标识符endl; return(buffer);char digitprocess(char buffer) /数字处理过程 int i=-1; char digittp20; int dtype; while (isdigit(buffer) digittp+i=buffer; fp.get(buffer); digittpi+1=0; dtype=search(digittp,5); coutlinenum: linenum String= digittpttt数据endl; return(buffer);char otherprocess(char buffer) /分界符、运算符、逻辑运算符、等 int i=-1; char othertp20; int otype,otypetp; othertp0=buffer; othertp1=0; if (otype=search(othertp,3) fp.get(buffer); othertp1=buffer; othertp2=0; if (otypetp=search(othertp,3) /判断该运算符是否是 /由连续的两个字符组成的 coutlinenum: linenum String= othertpttt运算符endl; fp.get(buffer); goto out; else /单字符逻辑运算符 othertp1=0; coutlinenum: linenum String= othertpttt逻辑运算符endl; goto out; if (otype=search(othertp,4) /关系运算符 fp.get(buffer); othertp1=buffer; othertp2=0; if (otypetp=search(othertp,4) /判断该关系运算符是否是 /由连续的两个字符组成的 coutlinenum: linenum String= othertpttt关系运算符endl; fp.get(buffer); goto out; else /单字符逻辑运算符 othertp1=0; coutlinenum: linenum String= othertpttt逻辑运算endl; goto out; if (buffer=!) /=的判断 fp.get(buffer); if (buffer=) /cout!= (2,2)n; fp.get(buffer); goto out; else if (otype=search(othertp,2) /分界符 coutlinenum: linenum String= othertpttt分界符endl; fp.get(buffer); goto out; if (buffer!=n)&(buffer!= ) cout错误！,字符非法tttbufferendl; fp.get(buffer); out: return(buffer); void main() int i; for (i=0;i=50;i+) lableconsti= ;/用于保存标识符 if (!fp) cout文件打开错误！endl; else fp.get (cbuffer); while (!fp.eof() if(cbuffer=n) linenum+; fp.get(cbuffer); else if (isalpha(cbuffer) cbuffer=alphaprocess(cbuffer); else if (isdigit(cbuffer) cbuffer=digi