Iterate elements of array using pointer

Question

I try execute code:

char* m[3] = {"123", "456", "789"};
for(char* st=*m; st!=0; st=*(m+1))
{
    cout <<st;
} 

but it hung up and print: 123456456456...

Answer 1

The loop you wrote is invalid

char* m[3]={"123","456","789"};
for(char* st=*m;st!=0; st=*(m+1))
{
    cout <<st;
} 

Expression *m has type char * and array m does not contain NULL pointer. So condition st!=0; is wrong. And the pointer always will point the same element because expression st=*(m+1) gives always the second element of the array

Also take into account that the correct definition of the array will be

const char* m[3] = { "123", "456", "789" };

because it is an array of pointers to string literals and string literals may not be changed.

You could use simply the range based for statement

const char* m[3] = { "123", "456", "789" };
for ( const char* st : m )
{
    cout <<st << std::endl;
} 

Or you could use iterators in the loop. For example

const char* m[3] = { "123", "456", "789" };
for ( auto it = std::begin( m ); it != std::end( m ); ++it )
{
    cout << *it << std::endl;
} 

And you could use standard algorithm std::copy

#include <iostream>
#include <algorithm>
#include <iterator>

//,,, 
const char* m[3] = { "123", "456", "789" };
std::copy( std::begin( m ), std::end( m ),
           std::ostream_iterator<const char *>( std::cout, "\n" ) );