Cara membuat tokenizer mendeteksi ruang kosong saat menggunakan strtok() [duplikat]

Kemungkinan Duplikat:
Cara membuat tokinezer mendeteksi ruang kosong saat menggunakan strtok()

Saya sedang merancang program c++, di suatu tempat dalam program saya perlu mendeteksi apakah ada yang kosong (token kosong) di sebelah token yang digunakan, misalnya.

if(token1==start)
{   
   token2=strtok(NULL," ");
   if(token2==NULL)
   {LCCTR=0;}
   else 
   {LCCTR=atoi(token2);}

jadi di bagian sebelumnya token1 menunjuk ke start , dan saya ingin memeriksa apakah ada nomor di sebelah start , jadi saya menggunakan token2=strtok(NULL," ") untuk menunjuk ke token berikutnya tetapi sayangnya fungsi strtok tidak dapat mendeteksi ruang kosong sehingga memberi saya kesalahan saat dijalankan"INVALID NULL POINTER" bagaimana cara memperbaikinya atau adakah fungsi lain yang digunakan untuk mendeteksi ruang kosong

#include <iostream>
#include<string>        
#include<map>
#include<iomanip>
#include<fstream>
#include<ctype.h>



using namespace std;
const int MAX=300;

int LCCTR;
int START(char* token1);
char* PASS1(char*token1);

void tokinizer()
{
   ifstream in;                 
   ofstream out;                

   char oneline[MAX];           
   in.open("infile.txt");       
   out.open("outfile.txt");


if(in.is_open())        
   {
       char *token1;
       in.getline(oneline,MAX); 
       token1 = strtok(oneline," \t");
       START (token1);
        //cout<<'\t';

 while(token1!=NULL)
  { 

            //PASS1(token1);
            //cout<<token1<<" ";


            token1=strtok(NULL," \t");

            if(NULL==token1)
            {//cout<<endl;
            //cout<<LCCTR<<'\t';
            in.getline(oneline,MAX);
            token1 = strtok(oneline," \t");
            }

    }
 }
   in.close();
   out.close();

}
int START(char* token1)
{
    string start("START");
    char*token2;
    if(token1 != start)
    {LCCTR=0;}

    else if(token1==start)
    {   
        token2=strchr(token1+2,' ');
        cout<<token2;
        if(token2==NULL)
        {LCCTR=0;}
        else 
       {LCCTR=atoi(token2);
        if(atoi(token2)>9999||atoi(token2)<0){cout<<"IVALID STARTING ADDRESS"<<endl;exit(1);}
        }   
    }
    return LCCTR;

}
char* PASS1 (char*token1)
{       
    map<string,int> operations;
    map<string,int>symtable;
    map<string,int>::iterator it;
    pair<map<string,int>::iterator,bool> ret;
    char*token3=NULL;
    char*token2=NULL;

    string test;
    string comp(" ");
    string start("START");
    string word("WORD");
    string byte("BYTE");
    string resb("RESB");
    string resw("RESW");
    string end("END");

        operations["ADD"] = 18;
        operations["AND"] = 40;
        operations["COMP"] = 28;
        operations["DIV"] = 24;
        operations["J"] = 0X3c;
        operations["JEQ"] =30;
        operations["JGT"] =34;
        operations["JLT"] =38;
        operations["JSUB"] =48;
        operations["LDA"] =00;
        operations["LDCH"] =50;
        operations["LDL"] =55;
        operations["LDX"] =04;
        operations["MUL"] =20;
        operations["OR"] =44;
        operations["RD"] =0xd8;
        operations["RSUB"] =0x4c;
        operations["STA"] =0x0c;
        operations["STCH"] =54;
        operations["STL"] =14;
        operations["STSW"] =0xe8;
        operations["STX"] =10;
        operations["SUB"] =0x1c;
        operations["TD"] =0xe0;
        operations["TIX"] =0x2c;
        operations["WD"] =0xdc;



        if(operations.find("ADD")->first==token1)
        {   token2=strtok(NULL," ");
            //test=token2;
            cout<<token2;
            //if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            //else{LCCTR=LCCTR+3;}
        }
        /*else if(operations.find("AND")->first==token1)
        {   token2=strtok(NULL," ");
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("COMP")->first==token1)
        {   token2=token1+5;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("DIV")->first==token1)
        {   token2=token1+4;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("J")->first==token1)
        {   token2=token1+2;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("JEQ")->first==token1)
        {   token2=token1+5;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("JGT")->first==token1)
        {   token2=strtok(NULL," ");
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("JLT")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("JSUB")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("LDA")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("LDCH")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("LDL")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("LDX")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("MUL")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("OR")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("RD")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("RSUB")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("STA")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("STCH")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("STL")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("STSW")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("STX")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("SUB")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("TD")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("TIX")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }
        else if(operations.find("WD")->first==token1)
        {   token2=token1+6;
            test=token2;
            if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);}
            else{LCCTR=LCCTR+3;}
        }*/

        //else if(


         if(word==token1)
        {LCCTR=LCCTR+3;}

        else if(byte==token1)
        {string test;
        token2=token1+7;
        test=token2;
            if(test[0]=='C')
            {token3=token1+10;
            test=token3;
            if(test.length()>15)
            {cout<<"ERROR"<<endl;
            exit(1);}
            }
            else if(test[0]=='X')
            {token3=token1+10;
            test=token3;
            if(test.length()>14)
            {cout<<"ERROR"<<endl;
            exit(1);}
            }
            LCCTR=LCCTR+test.length();
        }

        else if(resb==token1)
        {token3=token1+5;
        LCCTR=LCCTR+atoi(token3);}

        else if(resw==token1)
        {token3=token1+5;
        LCCTR=LCCTR+3*atoi(token3);}

        else if(end==token1)
        {exit(1);}



    /*else
    {   
        test=token1;
        int last=test.length();
        if(token1==start||test[0]=='C'||test[0]=='X'||ispunct(test[last])||isdigit(test[0])||isdigit(test[1])||isdigit(test[2])||isdigit(test[3])){}
        else    {
                token2=strtok(NULL," ");
                //test=token2;
                cout<<token2;
                if(token2!=NULL)
                {
                    symtable.insert( pair<string,int>(token1,LCCTR));
                    for(it=symtable.begin() ;it!=symtable.end() ;++it)
                        {/*cout<<"symbol: "<<it->first<<"      LCCTR: "<<it->second<<endl;}
                }
                else{}
        }
        }*/




return token3;

}
int main()
{
   tokinizer();
   return 0;
}