C语言编译原理：词法分析器实现与关键字识别

#include<stdlib.h> 
#include<stdio.h> 
#include<string.h> 


/******************************************* 
主函数 
********************************************/ 
main() 
{ 
int i; 
init(); /*初始化*/ 
i=scanner(); /*扫描源程序*/ 
if(i==1) 
printf("The answer is in 'output.txt':"); 
getch(); 
} 
/******************************************* 
初始化函数 
********************************************/ 
void init() 
{ 
char *key[]={" ","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语言所有关键字，共32个*/ 
char *limit[]={" ","(",")","[","]","->",".","!","++","--","&","~", 
"*","/","%","+","-","<<",">>","<","<=",">",">=","==","!=","&&","||", 
"=","+=","-=","*=","/=",",",";","{","}","#","_","'"};/*共38个运算、限界符*/ 

FILE *fp; 
int i; 
char c; 
fp=fopen("key.txt","w"); 
for(i=1;i<=32;i++) 
fprintf(fp,"%s\n",key[i]); 
fclose(fp);/*初始化关键字*/ 
fp=fopen("limit.txt","w"); 
for(i=1;i<=38;i++) 
fprintf(fp,"%s\n",limit[i]); 
c='"'; 
fprintf(fp,"%c\n",c); 
fclose(fp); /*初始化运算、限界符表*/ 
fp=fopen("id.txt","w"); 
fclose(fp); /*初始化标识符表*/ 
fp=fopen("constant.txt","w"); 
fclose(fp); /*初始化常数表*/ 
fp=fopen("output.txt","w"); 
fclose(fp); /*初始化输出文件*/ 

} 
/******************************************* 
十进制转二进制函数 
********************************************/ 
char * dtb(char *buf) 
{ 
int temp[20]; 
char *binary; 
int value=0,i=0,j; 
for(i=0;buf[i]!='\0';i++)