Expert: Zlatko - 1/27/2010

Question
Hi  Zlatko, I am trying to output ASCII chars from a to z but my function crashed. Pls advise me further. Tks.

Code:
#include <iostream>
#include <ctime>
#include <cstring>
#include <cstdlib>
using namespace std;

const int MAX = 10;

void outputChar (char*, int);


int main ()
{

  char* a;
  int size = MAX;
  srand (time(NULL));
  
  outputChar (a, 10);

}


//Output characters
void outputChar (char* a, int size)
{
  
  for (int i = 0; i < size; i++)
  {
     *a = static_cast <char> (rand () % 26 + 97); //Displaying ASCII char for lower case a to z.
     cout << &a [i] << "\t";
  }
  
  cout << endl;

}  

Answer
Hello Steve.

Your program is crashing because you are trying to put a byte into a location pointed at by 'a', but the 'a' pointer has not been initialized to point to a valid piece of memory.

In main, you need
char x[MAX];
char* a = x;

or
char a[MAX];

or
char* a = new char[MAX];

Any one of those will set aside MAX bytes in memory and set a to point to it.

In your for loop you want
a[i] = static_cast ....
not
*a = static_cast ....
because *a always refers to the start of the array

and you want
cout << a[i]
not
cout << &a[i]
because &a[i] gives the address of the i'th element.

OK?