Thread: Dynamic Array of Pointers to String

sir,

yesterday i tried to written a programme which takes some(any number) names as input and sort in ascending order.
Syntax is correct and programme works partially. really i don't know how to create dynamic array of pointers in C++. would you please help me.....
i am attaching my code with this post. please take look

Code:

#include<iostream.h>
#include<conio.h>
void main()
{
	clrscr();
                                                                             //*a = new (int*)[SIZE];
                                                                            //for(int j=0; j<SIZE; j++)
                                                                            //a[SIZE] = new int[SIZE];
	int size,p,m,n,i,j,k;
	cout<<"enter the no of names: ";
	cin>>size;
	char **pt=new char*[size];
	char *ptr;
	cout<<"\nEnter names: ";
	for(i=0;i<size;i++)
		cin>>*(pt+i);
	for(i=0;i<size-1;i++)
	{
		p=0;
		for(j=0;j<size-1-i;j++)
			for(k=0;;k++)
			{
				if(*(pt+p)+k=='\0')
				{
					p=j;
					break;
				}
				else if(*(pt+j+1)+k=='\0')
					break;
				m=*(*(pt+p)+k);
				n=*(*(pt+j+1)+k);
				if(m==n)
					continue;
				else if(n>m)
				{
					p=j+1;
					break;
				}
				else
					break;
			}
		ptr=*(pt+p);
		*(pt+p)=*(pt+size-i);
		*(pt+size-i)=ptr;
	}
	for(i=0;i<size;i++)
		cout<<*(pt+i);
	delete []pt;
	getch();
}

That code is horribly broken (not to mention an eyesore). Briefly, the main problem is that you are allocating an array of pointers, but neglecting to allocate memory to each element. Even so, you need to instruct 'cin' how many characters it is allowed to copy to on each read.

Fortunately, C++ comes with a powerful library of code, eg. the STL (Standard Template Library). In place of char* arrays, you can use std::string, and instead of 'raw' arrays, you have std::vector.

Code:

#include <iostream>
#include <vector>
#include <string>

int main( void )
{
	using namespace 
		std;
	string
		input;
	vector< string >
		lines;
	for( ;; )
	{
		cout << "Enter a line of text (or an empty line to exit) > ";
		if( !getline( cin, input ) || input.empty( ) )
			break;
		lines.push_back( input );	
	}
	if( !lines.empty( ) )
	{
		cout << "You entered: " << endl;
		// copy( lines.begin( ), lines.end( ), ostream_iterator< string >( cout, "\n" ) );
		for( size_t index = 0, limit = lines.size( ); index < limit; ++index )
		{
			cout << "[ " << index << " ] : '" << lines[ index ] << "'" << endl;
		}
	}
	return 0;
}

Much easier, no?