code.txt

# include < iostream >
using namespace ;
void main ( ) {
int result ;
result = 321 + 123  ;
50 + 20 + 874 + 123h32 ;
int result2 = 764 + 259 + void ;  
786das
}

Compiler.cpp

//============================================================================
// Task        : Compiler
// Description : Lexical Analyzer
// Name		   : Mahmoud Mohamed Fathy
// ID		   : 2012030135
//============================================================================

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

const string reservedWords[] = { "include", "iostream", "namespace", "using",
		"std", "void", "main", "int", "float", "char", "string" };
const char alphabets[] = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
		'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
		'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
		'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
const char numbers[] = { '1', '2', '3', '4', '5', '6', '7', '8', '9', '0' };
const char operators[] = { '+', '-', '*', '/', '%' };
const char specialSymbols[] ={';','{','}','(',')','=','\'','\"','<','>','#',',','!','.'};

bool isIdentifier(string word) {
	int counter = 0;
	for (int i = 0; i < word.size(); i++) {
		if (i == 0) {
			for (int j = 0; j < sizeof(alphabets); j++) {
				if (word.at(i) == alphabets[j]) {
					counter++;
					break;
				}
			}
		}
		else {
			for (int j = 0; j < sizeof(alphabets); j++) {
				if (word.at(i) == alphabets[j]) {
					counter++;
					goto end_else;
				}
			}
			for (int k = 0; k < sizeof(numbers); k++) {
				if (word.at(i) == numbers[k]) {
					counter++;
				}
			}
			end_else: ;
		}
	}
	if (counter == word.size())
		return true;
	return false;
}

bool isInteger(string word) {
	int counter = 0;
	for (int i = 0; i < word.size(); i++) {
		for (int j = 0; j < sizeof(numbers); j++) {
			if (word.at(i) == numbers[j]) {
				counter++;
				break;
			}
		}
	}
	if (counter == word.size())
		return true;
	return false;
}

bool isReservedWord(string word) {
	for (int i=0;i<sizeof(reservedWords)/sizeof(reservedWords[i]);i++) {
		if (word == reservedWords[i])
			return true;
	}
	return false;
}

bool isOperator(string word) {
	for (int i = 0; i < sizeof(operators); i++) {
		if (word.at(0) == operators[i])
			return true;
	}
	return false;
}

bool isSpecialSymbols(string word) {
	int counter = 0;
	for (int j = 0; j < sizeof(specialSymbols); j++) {
		if (word[0] == specialSymbols[j])
			return true;
	}
	return false;
}

int main() {
	ifstream myfile;
	string word;
	string previousWord;

	myfile.open("code.txt");
	while (!myfile.eof()) {
		myfile >> word;
		if (previousWord == "integer") {
			if (isOperator(word)) {
				cout << word << "\tis arithmetic operator\n";
				previousWord = "operator";
			} else {
				goto startOfElse;
			}
		}
		else if (previousWord == "operator") {
			if (isInteger(word)) {
				cout << word << "\tis Integer\n";
				previousWord = "integer";
			} else {
				cout<<word<<"\tError in position "<<myfile.tellg()<< " not integer after operator" << endl;
				goto startOfElse;
			}
		}
		else {
			startOfElse: if (isInteger(word)) {
				cout << word << "\tis Integer\n";
				previousWord = "integer";
			} else if (isReservedWord(word)) {
				cout << word << "\tis ReservedWord\n";
				previousWord = "reservedWord";
			} else if (isIdentifier(word)) {
				cout << word << "\tis Identifier\n";
				previousWord = "Identifier";
			} else if (isSpecialSymbols(word)) {
				cout << word << "\tis SpecialSymbols\n";
				previousWord = "SpecialSymbols";
			} else if (isOperator(word) && previousWord != "integer") {
				cout<<word<<"\tError in position "<<myfile.tellg()<<" not integer before operator";
				cout << word << "\tis arithmetic operator\n";
				previousWord = "operator";
			} else {
				cout<<word<<"\tError in position "<<myfile.tellg()<<" could not be resolved"<<endl;
				previousWord = "";
			}
		}
	}
	return 0;
}