hw to enter a null value in c++?

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C++

hai der...

i am writing a c++ program to accept an assebly source program as input(simply sayong i want to accept a set of string line) and display it.

here is the code...

#include<iostream.h>
#include<conio.h>
#include<string.h>
#include<alloc.h>
class source
{
	char label[10];
	char mnic[15];
	char op[10];
public:
	char* getdata()
	{
	cin>>label>>mnic>>op;
	return strdup(mnic);
	}
	char* display()
	{
	cout<<"\n"<<label<<"\t"<<mnic<<"\t"<<op;
	return strdup(mnic);
	}
};
class symtab
{
};
int main()
{
clrscr();
source obj1[15];
char *sptr;
int i=0;
do
{
sptr=obj1[i].getdata();
i++;
}while((strcmp(sptr,"end"))!=0);
i=0;
do
{
sptr=obj1[i].display();
i++;
}while((strcmp(sptr,"end"))!=0);
getch();
free(sptr);
return 0;
}

We enter three strings for each object (namely label,mnic,op).But the problem is that the code cant help if i did not want to enter a string for label.the c prompt waits until we enter all the three strings.how its possible not two enter a value.that is how i can enter a null value?


eg:

if i enter

name start 2000
g lda b
f end g

it shows output as the same given above.

i want to enter

name start 2000
lda b
f end g

how i can put the first enter as null?