编译原理及实现_附录B_词法分析程序 代码

词法分析子程序：
#include
#include
#include
#define keywordSum 10
char *keyword[keywordSum]={"if","else","for","while","do","int","read","write","char","real"};//添加的保留字char,real;
char singleword[50]="+ - * () {} , : ";
char doubleword[10]="> < = ! ";
char doubleword1[10]="& &";
char doubleword2[10]="||";
extern char Scanin[300],Scanout[300];
extern FILE * fin,*fout;
int TESTscan()
{
char ch,token[40];
int es=0,j,n;
printf ("请输入源程序文件名（包括路径）:");
scanf ("%s",Scanin);
printf ("请输入词法分析输出文件名（包括路径）:");
scanf ("%s",Scanout);
if ((fin=fopen(Scanin,"r"))==NULL)
{
printf("\n打开词法分析输入文件出错！\n");
return(1);
}
if((fout=fopen(Scanout,"w"))==NULL)
{
printf("\n创建词法分析输出文件出错！\n");
return(2);
}
ch=getc(fin);
while(ch!=EOF)
{
while (ch==' '|| ch=='\n'|| ch=='\t')ch=getc(fin);
if(isalpha(ch))
{
token[0]=ch;j=1;
ch=getc(fin);
while(isalnum(ch))
{
token[j++]=ch;
ch=getc(fin);
}

token[j]='\0';
n=0;
while ((nif(n>=keywordSum)
fprintf(fout,"%s\t%s\n","ID",token);
else
fprintf(fout,"%s\t%s\n",token,token);
}else if (isdigit(ch))
{
token[0]=ch;
j=1;
ch=getc(fin);
while (isdigit(ch))
{
token[j++]=ch;
ch=getc(fin);
}
token[j]='\0';
fprintf(fout,"%s\t%s\n","NUM",token);
}
else if (strchr(singleword,ch)>0)
{
token[0]=ch;token[1]='\0';
ch=getc(fin);
fprintf(fout,"%s\t%s\n",token,token);
}
else if (strchr(doubleword,ch)>0)
{
token[0]=ch;

ch=getc(fin);

if (ch==' = ')
{
token[1]=ch;token[2]='\0';
ch=getc(fin);
}
else
token[1]='\0';
fprintf(fout,"%s\t%s\n",token,token);
} //所加代码；
else if (strchr(doubleword1,ch)>0)//判断&& { token[0]=ch; ch=getc(fin); if(ch=='&')
{ token[1]=ch;
token[2]='\0';
ch=getc(fin);
}else


token[1]='\0';
fprintf(fout,"%s\t%s\n",token,token);
} //所加代码
else if (strchr(doubleword2,ch)>0)//判断||
{
token[0]=ch;
ch=getc(fin);
if(ch=='|')
{
token[1]=ch;
token[2]='\0';
ch=getc(fin);

}
else
token[1]='\0';
fprintf(fout,"%s\t%s\n",token,token);
} /所加代码
else if (ch=='/')
{
ch=getc(fin);
if (ch=='*')
{
char ch1;
ch1=getc(fin);
do
{
ch=ch1;ch1=getc(fin);}
while ((ch!='*'||ch1!='/')&&ch1!=EOF);
ch=getc(fin);
}
else
{
token[0]=ch;token[1]='\0';
fprintf(fout,"%s\t%s\n",token,token);
}
}
else
{
token[0]=ch;token[1]='\0';
ch=getc(

fin);
es=3;
fprintf(fout,"%s\t%s]\n","ERROR",token);
}
}
fclose(fin);
fclose(fout);
return(es);
}
主程序：
#include
#include
extern int TESTscan();
char Scanin[300],Scanout[300];
FILE *fin,*fout;
void main(){
int es=0;
es=TESTscan();
if(es>0)
printf("词法分析有错，编译停止！");
else printf("词法分析成功！ \n");
}