Ok

I have an assignment for school where we are building a compiler step by step each week. This week I have to make a syntax analyzer that picks out the errors from this text file below. In the source code I have provided below I have a lexical analyzer and a symbol able that will point the types and variables. That is there just so you can see what I am working with.

The syntax analyzer is supposed to point out errors in the text file file in lines 3 and 4. No semicolon and undeclared identifier.

What I am confused about is how do I get it so that my program can look for specific line in the text and list them onto the screen. Once I figure out this part I finish my assignment. Thanx in advance.

/////start of text file
main()

{

int i

j = 23;

}
///////end of text file

#include <stdio.h>
#include <stdlib.h>
#include <iostream> 
#include <string.h>
#include <sstream>
#include <fstream>
#include <ctype.h>
#include <conio.h>
#include <time.h>
#include <math.h>
#include <dos.h>
#include <iomanip>


using namespace std;
 

int main(int argc, char* argv[])
{
	
	 ifstream infile ("input.txt");/*assigning infile to to the input text otherwise 
						     the program will spit out all zeroes as the result.*/

	//Variables
	string Storeline;//Variable to store the line
	string token = "";//variable to store the token
	string Name = "";//variable to store the table name
	bool Finished = false;//boolean to determine end of line read
	string chump;//the string we use to input our text file
	
	
	//Structure for symbol table
	struct SymbolTable
	{
		string tokenType;
		string tokenName;
	}
	table[1000];//this will be a constructor of sorts

	//position in line read
	int position = 0;
	int a = 0;

cout<<"Enter the file name, don't forget to enter the txt extension as well.\n";
   cin >> chump;
     
     getline (infile, chump);/*gets the data from the txt file and converts it to a string.*/
	 
	if(!infile.is_open())//input.txt cannot be open then we get this error message.
	{
		cout << "cant open file!";
		return 0;
	}

	//Read til end of file
	do
	{
		Finished = false;
		
		//get line from input file
		getline(infile, Storeline);

		if(!infile.eof())
		{
			//do... while until line is read
			do
			{
				char character = Storeline[position++];
				if((character >= 'a' && character <= 'z') || (character >= 'A' && character <= 'Z'))
				{
					token = token + character;//here we tokenize each alphabetical character
				}
				else if(character == '(' || character == ')' || character == '{' || character == '}' || character == ';'
					|| character == '=' || character == '+' || character >= 0 || character <= 0)
					//We tokenize the symbols that are not letters 
				{
					if(token == "int" || token == "double" || token == "char")
						//here we specifiying what the symbol table should look for
					{
						table[a].tokenType = token;//We search our symbol table for the Token types
						while(character != ';')//I need this semicolon so the variable names will show up.
						{
							character = Storeline[position++];
							Name = Name + character;
						}
						table[a].tokenName = Name;//We search our symbol table or the Token Names
						a++;
					}
					cout << token << endl;
					if(Name != "")
					{
						cout << Name << endl;
					}
					token = "";//displays variable type
					Name = "";//displays variable itself
					cout << character << endl;
				}
				if (position >= Storeline.length())
				{
					Finished = true;
					position = 0;
				}
			}while(!Finished);
		}
	}while(!infile.eof());

	//close input file
	infile.close();

	//table format
	cout << "Type      Variable Name\n";

	//loop to display each of the symbol tables data
	for(int f = 0; f < a; f++)
	{
		cout << table[f].tokenType << "        " << table[f].tokenName << endl;
	}

	system("pause");

	return 0;
}

So what exactly is the problem? It looks like if you add a cout statement

getline(infile, Storeline);
std::cout << Storeline;

you'd have what you asked for (simply displaying each line of the file on the screen)?

So what exactly is the problem? It looks like if you add a cout statement

getline(infile, Storeline);
std::cout << Storeline;

you'd have what you asked for (simply displaying each line of the file on the screen)?

I need it to pick out the C++ errors in the text and I'm not sure how exactly how to do that.

Isn't that the subject matter of your course?

For this week yes but the book gives me a real complicated explanation on how one is supposed to to do this. Maybe one of you guys that done such a program can offer me a simplified explanation. Until then, I'll try out what daviddoria told me.

what exactly is the answer in that problem??