code is not working properly....

#include<iostream>
#include<conio.h>
#include<string>
#include<fstream>
#include<ctype.h>
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<25;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<4;i++)
{
if(str == MDPOperators[i])
{
flag = 1;
break;
}
}
if(flag == 1)
{
return "MDP Operators";
}
else
{
for(int i=0;i<3;i++)
{ 
if(str == A_SOperators[i])
{
flag1 = 1;
break;
}
}
if(flag1 == 1)
{
return "A_S Operator";
}
else
{
for(int i=0;i<9;i++)
{ 
if(str == RelOperators[i])
{
flag2 =1;
break;
}
}
if(flag2 == 1)
return "Relational Operator";
else
{
for(int i=0;i<3;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";
} 
}
}
}
}
}
}
}
}

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;

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 --> reserved word\n"; 
} 
else
{

flag = isidentifier(str);

if(flag == 1)
{
ofs<<str<<"\t --> error\n";
flag = 0;

}
else
{
ofs<<str<<"\t --> identifier\n";
}
}



}
else
{
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
ofs<<str<<"\t -->"<<strch<<"\n";
}
} 

}

str=""; 
}
else
{
str=str+strline[j]; 
} 
} 




}


cout<<"output file is generated : output.txt";


getch();
return 0;
}

static int __CLRCALL_OR_CDECL compare(const _Elem *_First1, const _Elem *_First2,
        size_t _Count)
        {   // compare [_First1, _First1 + _Count) with [_First2, ...)
        return (_Count == 0 ? 0
            : _CSTD memcmp(_First1, _First2, _Count));
        }