no output is generated5....

#include<iostream>
#include<conio.h>
#include<string>
#include<fstream>
using namespace std;

/* The grammar follwed by this analyser is : you have to give a blank to differentite between two different entities, for eg 
instead of writing "int c=a+b;", write it as "int c = a + b ;".

To execute this program first create an "input.txt" file where the program is written or specify the path of the file which has 
to be analysed, after compiling an "output.txt" file will be created where you have stored the program.
*/

bool keycheck(string str)
{
	string keyword[] ={"num","alpha","fnum","lnum","snum","string","struct","bool","true","false","for","while","repeat","void","main()","if","else","switch","default","case","break","continue","return","goto"};
	int flag=0;
    if(!(str[0]>='a' && str[0]<='z'))
		return false;
	for(int i=0;i<2;i++)
	{
		if(str == keyword[i])
		{
			flag = 1;
			break;
		}
	}
	if(flag == 1)
        return true;
	else
		return false;
} 

string opcheck(string str)
{
	string AsgOperators ="=";
    string MDPOperators[5] ={"*","/","^"};
    string A_SOperators[4]={"+","-"};
    string RelOperators[10]={">=","<=","<",">","||","!="};
    string NOT="!";
    string OR="$";
    string AND="&";
    string S_C[2]={"SRT","CRT"};
    int flag1=0,flag2=0,flag=0,flag3=0,flag4=0,flag5=0,flag6=0,flag7=0;

    for(int i=0;i<3;i++)
	{
		if(str == MDPOperators[i])
		{
			flag = 1;
			break;
		}
	}
	if(flag == 1)
	{
		return "MDP Operators";
	}
	else
	{
		for(int i=0;i<2;i++)
		{ 
			if(str == A_SOperators[i])
			{
				flag1 = 1;
				break;
			}
		}
		if(flag1 == 1)
		{
			return "A_S Operator";
		}
		else
		{
			for(int i=0;i<6;i++)
			{ 
				if(str == RelOperators[i])
				{
					flag2 =1;
					break;
				}
			}
			if(flag2 == 1)
				return "Relational Operator";
			else
			{
				for(int i=0;i<2;i++)
				{ 
					if(str == S_C[i])
					{
						flag3 =1;
						break;
					}
				}
				if(flag3 == 1)
					return "S_C Operators";
				else
				{
					if(str == "=")
					{
						flag4=1;
					}
					if(flag4 == 1)
						return "Asg Operator";
					else
					{
						if(str == "!")
						{
							flag5=1;
						}
						if(flag5 == 1)
							return "NOT";
						else
						{
							if(str == "$")
							{
								flag6=1;
							}
							if(flag6 == 1)
								return "OR";
							else
							{
								if(str == "&")
								{
									flag7=1;
								}
								if(flag7 == 1)
								{
									return "AND";
								}
								else
								{
									return "Error";
								} 
							}
						}
					}
				}
			}
		}
	}
}
string Punctuatorcheck(string str)
{
	string punctuators[]={".",",","/>","{","}","(",")","]","["};
    for(int i=0; i<9;i++)
                    {
                        if(str==punctuators[i])
                        {
							return "Punctuator";                            
                        }
                    }
                    return "Error";
                }


int ischar(char c)
{
	if((c>='A' && c<'Z') || (c>='a' && c<='z'))
		return 1;
    else
		return 0; 
} 

int isnum(char c)
{
	if(c>='0' && c<='9')
		return 1;
    else
		return 0;
}

int isnums(string str)
{
	int flag=0;
	for(int i = 0;i<str.length();i++)>
	{
		if(!isnum(str[i]))
		{
			if(str[i] != '.') 
			{
				flag=1;
				break;
			}
		}
	}
	if(flag == 1)
		return 0;
	else
		return 1;
}

int isidentifier(string str)
{
	int flag =0;
    for(int i=1;i<str.length();i++)>
	{
		if(!ischar(str[i]))
		{
			if(!isnum(str[i]))
			{
				if(str[i] != '_')
				{
					if(str[i] == '[')
					{
						i++;
						for(;str[i]!= ']';)
						{
							if(!isnum(str[i]))
							{
								flag =1;
								break;
							}
							i++;
						}
					}
					else
					{ 
						flag = 1;

					}
					if(flag ==1)
						break;
				}
			}
		}
	}
return flag;
}

int main()
{
	ifstream ifs("input.txt");
    ofstream ofs("output.txt");
	int line=0,flag=0;
	bool check;
	string str="",strch,strline,strp;
	while(!ifs.eof())
	{
		getline(ifs,strline);
		line++;
		ofs<<"---------\n";
		ofs<<line<<"\n";
		strline = strline + " ";
		for(int j=0;j<strline.length();j++)>
		{ 
			if(strline[j] ==' ' || strline[j]=='\t')
			{
				if(str != "")
				{
					if(ischar(str[0]))
					{
						check = keycheck(str);

						if(check)
						{
							ofs<<str<<"\t --> Keywords\n"; 
						} 
						else
						{
							flag = isidentifier(str);
							if(flag == 1)
							{
								ofs<<str<<"\t --> Error\n";
								flag = 0;

							}
							else
							{
								ofs<<str<<"\t --> Identifier\n";
							}
						}
						if(isnum(str[0]))
						{
							if(isnums(str))
								ofs<<str<<"\t -->Number\n";
							else
								ofs<<str<<"\t -->Error\n";
						}
						else
						{
							strch = opcheck(str);
							if(strch == "Error")
								ofs<<str<<"\t -->"<<strch<<"\n";
							else
							{
								strch = Punctuatorcheck(str);
								if(strp == "Error")
									ofs<<str<<"\t -->"<<strp<<"\n";
								else
									ofs<<str<<"\t -->"<<strp<<"\n";
							}
						}
						str=""; 
					}
					else
					{
						str=str+strline[j]; 
					} 
				} 
			}
		}
	}
			cout<<"output file is generated : output.txt";
			getch();
			return 0;
}</fstream></string></conio.h></iostream>