Thread: lexical analyzer code error

i am running this code but i am geting few errors .as shown in the image

Code:

#include "stdafx.h"
#include <iostream>
#include <conio.h>
#include <string>






using namespace System;


#define T_SEMICOLON ';'
#define T_LPAREN '('
#define T_RPAREN ')'
#define T_ASSIGN '='
#define T_DIVIDE '/'


#define T_WHILE 257
#define T_IF 258
#define T_RETURN 259


#define T_IDENTIFIER 268
#define T_INTEGER 269
#define T_DOUBLE 270
#define T_STRING 271


#define T_END 349
#define T_UNKNOWN 350




struct token_t {
	int type;
	union{
		char stringValue [256];
		int intValue;
		double doubleValue;
	} val;
};
//array<System::String ^> ^args
int main(int argc,char *argv[])
{
    
	
	struct token_t token; 
	InitScanner();
	while (ScanOneToken(stdin, &token) !=T_END);
	
		
		
	
	return 0;
	
}
static void InitScanner()
{
create_reserved_table();
insert_reserved("WHILE",T_WHILE)
insert_reserved("IF",T_IF)
insert_reserved("RETURN",T_RETURN)
}
static int ScanOneToken(FILE *fp,struct token_t *token)
{
	int i,ch,nextch;
	ch =getc(fp);
	while (isspace(ch))
		ch = getc(fp);
	switch(ch)
	{
	case'/':
		nextch=getc(fp);
		if(nextch=='/'|| nextch =='*');
		else
			ungetc(nextch,fp););
	case';':case',':case'=':
		token->type =ch;
		return ch;


	case 'A':case'B':case'C':case'D':case'E':case'F':case'G':case'H':case 'I':case'J':case'K':case'L':case'M':case'N':case'O':case'P':
	case 'Q':case'R':case'S':case'T':case'U':case'V':case'W':case'X':case'Y':case'Z':
		token->val.stringValue[0]=ch;
		for (i=1;isupper(ch =getc(fp));i++)
			token->type =lookup_reserved(token->val.stringValue);
		return token->type;
    case 'a':case'b':case'c':case'd':case'e':case'f':case'g':case'h':case 'i':case'j':case'k':case'l':case'm':case'n':case'o':case'p':
	case 'q':case'r':case's':case't':case'u':case'v':case'w':case'x':case'y':case'z':
			token->type = T_IDENTIFIER;
			token->val.stringValue[0] = ch;
			for (i=1; islower(ch= getc(fp));i++)
				token->val.stringValue[i]=ch;
			ungetc(ch,fp);
			token->val.stringValue[i] ='\0';
			if (lookup_symtab(token->val.stringValue)==NULL)
				add_symtab(token->val.stringValue);
			return T_IDENTIFIER;
			case '0':case'1':case'2':case'3':case'4':case'5':case'6':case'7':case '8':case'9':
				token->type=T_INTEGER;
				token->val.intValue = ch -'0';
				while (isdigit(ch = getc(fp)))
					token->val.intValue = token->val.intValue*10+ch-'0';
				ungetc(ch,fp);
				return  T_INTEGER;


			case EOF:
				return T_END;
				
			default:
				token->val.intValue = ch;
				token->type = T_UNKNOWN;
				return T_UNKNOWN;
	}
}

You need to declare the functions InitScanner() and ScanOneToken() before using them. Best place is before main()
Kurt

Originally Posted by ZuK

You need to declare the functions InitScanner() and ScanOneToken() before using them. Best place is before main()
Kurt

i am still getting errors doing that too

you have to define and declare all the other missing functions as well.

actually i am doing it from this article http://dragonbook.stanford.edu/lectu...l-Analysis.pdf i am new to c++ can you help me out with this

Originally Posted by achme

actually i am doing it from this article http://dragonbook.stanford.edu/lectu...l-Analysis.pdf i am new to c++ can you help me out with this

I can help if you have a specific question.
Kurt

ok like if i want to make create_reserved_table(); so how am i going to do that

As this is c++ you don't have to do much to create a table of reserved words.
a std::map<std::string,int> will do.

insert_reserved would just add the reserved word to that map, and lookup_reserved would just look up the token type given a string.
Kurt