0921 词法分析程序

#include <stdio.h>
#include <string.h>
#include <iostream.h>
/*全局变量*/
char * chr_form[100];
int q=0,temp;
char *word[6]={"begin","end","if","then","do","while"};
int i=0,j=0,k=0,t=0;
char ch,str[20];
char *ss[100];
char form[1000];
void analyze();
void main ()
{
	printf("输入字符串，以*结束：");
	form[0]=cin.get();
	for(q=1;form[q-1]!='##';q++)
	{
		form[q]=cin.get();
		if(form[q]=='*')
		{
			printf("你输入是:
");
			cout.write(form,q);
			break;
		}
	}
	cout<<endl;
	analyze();

}

void GetChar()
{
	ch=form[k];
	k++;
}
void getbc()
{
	while(ch==' ')
	{
		
		GetChar();
	}
}
void concat()
{
	str[i]=ch;
	i++;
}
bool isletter()
{
	if(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A')))
		return(1);
	else
		return(0);
}
bool isdigit()
{
if(((ch)<='9')&&((ch)>='0'))
return (1);
else
return (0);
}
int reserve()
{
	for(int q=0;q<5;q++)
	{
		if(strcmp(word[q],str)==0)
			return q;
		if(q==4)
			return -1;
	}
}
void retract()
{
	k--;
	ch=NULL;
}
char *insertld()
{
	chr_form[j]=str;
	j++;
	return chr_form[0];
}
char * insertconst()
{
	ss[t]=str;
	t++;
	return ss[0];
}
int code;
void output(int a,char *p1,char *p2)
{
	cout<<"	类别码:"<<a<<"	 单词值:";
		while(p1<=p2)
		{
			printf("%s",*p1);
			p1++;
		}
		cout<<endl;
}

void analyze()
{
	GetChar();
	getbc();
	if(isletter())
	{
		while (isletter()||isdigit())
		{
			concat();
		GetChar();
		}
		retract();
		code=reserve();
		switch(code)
		{
		case 0:cout<<"单词:" <<str<<"  类别码为: "<<1<<endl;break;

		case 1:cout<<"单词:" <<str<<"  类别码为: "<<2<<endl;break;
	
        case 2:cout<<"单词:" <<str<<"  类别码为: "<<3<<endl;break;

      case 3:cout<<"单词:" <<str<<"  类别码为: "<<4<<endl;break;
       case 4:cout<<"单词:" <<str<<"  类别码为: "<<5<<endl;break;
      case 5:cout<<"单词:" <<str<<"  类别码为: "<<6<<endl;break;

	  default:
		  cout<<"单词:" <<str<<"  类别码为: "<<6<<endl;break;


	}
	}
	else
	{
		if( isdigit())
		{
          while(isdigit()||ch=='.')
		  {
			  concat();
			  GetChar();
		  }
		  retract();
		  cout<<"单词:"<<str<<"  类别码为："<<7<<endl;
		}
		else
		{
			switch(ch)
			{
			case'+': printf("+ 类别码为13
");break;
            case'-':  printf("- 类别码为14
");break;
		    case'*':  printf("* 类别码为15
");break;
			case'/':  printf("/ 类别码为16
");break;
			case';':  printf("; 类别码为26
");break;;
			case'(':  printf("( 类别码为27
");break;
			case')':  printf(") 类别码为58
");break;
			case'#':  printf("#类别码为0
");;break;
		
			case':':GetChar();
				if(ch=='=')
				{
					cout<<"单词::=  类别码为: "<<18<<endl;break;
				}
				else
				{
					retract();
					cout<<"单词::   类别码为: "<<17<<endl;break;
				}
			case'=':cout<<"单词:=  类别码:"<<24<<endl; break;
			case'>':GetChar();switch(ch)
					{
			case'=':cout<<"单词:>=  类别码:"<<24<<endl;break;
			default: retract;
				cout<<"单词:=> 类别码:"<<12<<endl;break;
					}
			case'<':GetChar();
				switch(ch)
				{
				case'=':cout<<"单词:<=  类别码:"<<21<<endl;break;
                case'>':cout<<"单词:<>  类别码:"<<22<<endl;break;
               default: retract();
					cout<<"单词:<  类别码:"<<20<<endl;break;
			}
		}
	}
	}

	while(k<q)
	{
		for(int p=0;p<50;p++)
			str[p]='';
		i=0;
		analyze();
	}
}