一个简单的C词法分析器 能识别数字,标志符(关键字,变量)和一些运算符.....rar

#include <stdio.h> #include <string.h> //#include <process.h> //#include <windows.h> #define MAX 50 /* if,else,while,do,char,int,float,long,for,main,void return,exit,static,struct,typdef, goto,extern,swich,case,continue,break*/ void main() { FILE *in,*out;/*存放输入字符串和输出单词串的文件*/ char arr[MAX];/*arr数组存放单词符号*/ char currentchar;/*currentchar存放当前输入字符*/ int i=0;/*arr数组的一个指针*/ /*以读方式打开输入文件*/ if((in=fopen("infile.txt","r"))==NULL) { printf("can not open file\n"); return; //exit(0); } /*以写方式打开输出文件*/ if((out=fopen("outfile.txt","w"))==NULL) { printf("cannout open outfile\n"); return; //exit(1); } //去掉开头空格 currentchar=fgetc(in); while(currentchar==' ') { currentchar=fgetc(in); } // int ch; while(currentchar!='@') { /*常数部分判断*/ if((currentchar>='a'&&currentchar<='z')||(currentchar>='A'&&currentchar<='Z')|| (currentchar>='0'&&currentchar<='9')||currentchar=='('||currentchar==')'|| currentchar=='{'||currentchar=='}'||currentchar=='>'||currentchar=='<'|| currentchar==';'||currentchar==':'||currentchar=='+'||currentchar=='-'|| currentchar=='*'||currentchar=='/'||currentchar=='='||currentchar=='!'|| currentchar=='&'||currentchar=='\n'||currentchar==' '||currentchar=='['|| currentchar==']'||currentchar=='"'||currentchar=='\''||currentchar=='\\' ||currentchar==','||currentchar=='%'||currentchar==' ') // 字母，数字，() {} <> : ; + _ * / = ! & \n [] " ' \ { i=0;//清空arr字符数组 if(currentchar>='0'&&currentchar<='9') { arr[i++]=currentchar; currentchar=fgetc(in);//再读入下一个字符 while(currentchar>='0'&&currentchar<='9') { arr[i++]=currentchar; currentchar=fgetc(in); } if(currentchar!='.')//如果当前读入的符号不为小数点，则常数读完毕，输出此常数 { arr[i++]='\0'; fprintf(out,"%s%d,%c%s%c%s\n","(",100,'"',arr,'"',")");//数字种码为100 } else//当前字符为小数点则继续向下读入 { arr[i++]=currentchar; currentchar=fgetc(in); while(currentchar>='0'&&currentchar<='9') { arr[i++]=currentchar; currentchar=fgetc(in); } arr[i++]='\0'; fprintf(out,"%s%d,%c%s%c%s\n","(",100,'"',arr,'"',")"); } while(currentchar==' '||currentchar==' ') { currentchar=fgetc(in); } } /*判断标识符和关键字部分*/ if((currentchar>='a'&&currentchar<='z')||(currentchar>='A'&&currentchar<='Z')) { i=0;//清空arr字符数组 while((currentchar>='a'&&currentchar<='z')||(currentchar>='0'&&currentchar<='9') ||(currentchar>='A'&&currentchar<='Z')) { arr[i++]=currentchar; currentchar=fgetc(in); } //把字符数组arr和关键字表比较，判断单词串是关键字还是标识符 arr[i++]='\0'; if(strcmp(arr,"if")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",0,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"else")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",1,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"while")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",2,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"do")==0) { fprintf(out,"%s%d,%c%s%c%s\n","(",3,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"for")==0) { fprintf(out,"%s%d,%c%s%c%s\n","(",4,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"int")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",5,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"char")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",6,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"float")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",7,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"struct")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",8,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"typedef")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",9,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"static")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",10,'"',arr,'"',")"); //urrentchar=fgetc(in); } else if(strcmp(arr,"void")==0) { fprintf(out,"%s%d,%c%s%c%s\n","(",11,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"main")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",12,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"return")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",13,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"exit")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",14,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"extern")==0) { fprintf(out,"%s%d,%c%s%c%s\n","(",15,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"goto")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",16,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"switch")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",17,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"case")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",18,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"continue")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",19,'"',arr,'"',")"); //currentchar=fgetc(in); } else if(strcmp(arr,"break")==0) {fprintf(out,"%s%d,%c%s%c%s\n","(",20,'"',arr,'"',")"); //currentchar=fgetc(in); } else {fprintf(out,"%s%d,%c%s%c%s\n","(",60,'"',arr,'"',")"); //currentchar=fgetc(in); } }//0到59是关键字，60是变量名，100 是数字，60到99可以设为运算符等 while(currentchar==' '||currentchar==' ') { currentchar=fgetc(in); } //判断标识符包括：+, -, *, /, (, ), {, }, <, >, ;, :, !=, >=, <=, ==, =. if(currentchar=='+') { fprintf(out,"%s%d,%c%c%c%s\n","(",61,'"',currentchar,'"',")"); currentchar=fgetc(in); } while(currentchar==' '||currentchar==' ') { currentchar=fgetc(in); } if(currentchar=='-') { fprintf(out,"%s%d,%c%c%c%s\n","(",62,'"',currentchar,'"',")"); currentchar=fgetc(in); } while(currentchar==' '||currentchar==' ') { currentchar=fgetc(in); } if(currentchar=='*') { fprintf(out,"%s%d,%c%c%c%s\n","(",63,'"',currentchar,'"',")"); currentchar=fgetc(in); } while(currentchar==' '||currentchar==' ') { currentchar=fgetc(in); } if(currentchar=='/') { i=0; arr[i++]=currentchar; currentchar=fgetc(in