Thread: Yet another problem with substr

I'm writing a lexer to generate a list of tokens from a std::string..
The string called section is not getting the values it should...(if there is nothing else wrong)..
The code is as follows...the problem(almost surely) is at the bold regions..

Code:

#include "lexer.h"
#include "token.h"
#include <iterator>
#include <string>
//#include <iostream>
//using std::cout;
using std::list;
using std::string;
list<token> tokenize(string s)
{
    list<token> lt;
    string::iterator sit;
    enum State {nil,num,ifr,sym} state(nil);
        //^nothing,number,identifier,other single char symbols
    for(sit=s.begin();sit!=s.end();sit++)
    {
        static int start,length;
        static char cur; //current char
        static string section; //substr'ed string
        static bool uniflag(false);
            //If a section is ready to be pushed_back
        cur = *sit;
        if(cur>='0'&&cur<='9')
        {
            if(state==nil)
            {
                state=num;
                start = sit - s.begin();
            }
            else if(state==ifr)
            {
                state=num;
                
                length=sit - s.begin() - start ;
                section = s.substr(start,length);
                start = sit - s.begin();
                uniflag = true;
            }

        }
        else if(cur>='a'&&cur<='z')
        {
            if(state==nil)
            {
                state=ifr;
                start = sit - s.begin();
            }
            else if(state==num)
            {
                state=ifr;
                
                length=sit - s.begin() - start;
                section = s.substr(start,length);       
                start = sit - s.begin();
                uniflag = true;
            }


        }
        else
        {
            state = sym;
            section = cur;
            uniflag = true;
        }

        if(uniflag==true)
        {
//            cout<<'\n'<<section<<'\n';
            lt.push_back(token(section));
        }

    }

    return lt;
}

Did so...edited the original...but same problem remains...
i.e...'section' still isn't getting anything but garbage..

EDIT: Previous stuff gone.

start is an int, not an iterator. That's what I was missing.

Your sym case is broken, since it doesn't reset things (or, if it's the first case, set things). Hard to tell what's up with the rest but will keep looking. Sorry about the bogus stuff that was here earlier.

Corrected it..Everything works as expected ..now.... Any other suggestion..?

Code:

#include "lexer.h"
#include "token.h"
#include <iterator>
#include <string>
//#include <iostream>
//using std::cout;
using std::list;
using std::string;
list<token> tokenize(string s)
{
    list<token> lt;
    string::iterator sit;
    enum State {nil,num,ifr,sym} state(nil);
        //^nothing,number,identifier,other single char symbols
    int start,length;
    char cur; //current char
    string section; //substr'ed string
    bool uniflag(false);
        //If a section is ready to be pushed_back
    for(sit=s.begin();sit!=s.end();sit++)
    {
        uniflag = false;
        cur = *sit;
        if(cur>='0'&&cur<='9')
        {
            if(state==nil)
            {
                state=num;
                start = sit - s.begin();
            }
            else if(state==ifr)
            {
                state=num;

                length=sit - s.begin() - start ;
                section = s.substr(start,length);
                start = sit - s.begin();
                uniflag = true;
            }
            else if(state==sym)
            {
                state=num;

                length=sit - s.begin() - start ;
                section = s.substr(start,length);
                start = sit - s.begin();
                uniflag = true;
            }

        }
        else if(cur>='a'&&cur<='z')
        {
            if(state==nil)
            {
                state=ifr;
                start = sit - s.begin();
            }
            else if(state==num)
            {
                state=ifr;

                length=sit - s.begin() - start;
                section = s.substr(start,length);
                start = sit - s.begin();
                uniflag = true;
            }
            else if(state==sym)
            {
                state=ifr;

                length=sit - s.begin() - start;
                section = s.substr(start,length);
                start = sit - s.begin();
                uniflag = true;
            }

        }
        else //if(state==sym) ..
        {
            if(state==nil)
            {
                state=sym;
                start = sit - s.begin();
            }
            else if(state==num)
            {
                state=sym;
                length=sit - s.begin() - start;
                section = s.substr(start,length);
                start = sit - s.begin();
                uniflag = true;
            }
            else if(state==ifr)
            {
                state=sym;
                length=sit - s.begin() - start;
                section = s.substr(start,length);
                start = sit - s.begin();
                uniflag = true;
            }
        }
        if(uniflag==true)
        {
//            cout<<'\n'<<section<<'\n';
            lt.push_back(token(section));
        }
        if((sit == s.end()-1))
        {
            length = s.end()-s.begin()-start;
            section = s.substr(start,length);
//            cout<<'\n'<<section<<'\n';
            lt.push_back(token(section));
        }
    }
    return lt;
}

The main part of the code is almost repeated 3 times...is there a way to make it common for the 3 cases(a function would require so many arguments ..that it'd become tedious)?....