Why the program is crushing !!??

Question

#include<iostream>
using namespace std;

int main()
{
int *ptr;
*ptr=5;
cout<<*ptr;
return 0;
}

The programming is crushing when ran in code::Blocks 16.01
it's an integer pointer which takes 4 bytes of memory. the value "5" should have got assigned in it and give output . Rather , the program is chushing.

Answer 1

int* ptr = new int;

ptr will point to a rubbish adress without this assignment. The new keyword is there to actually say: I want memory for a new variable. And it returns the new variables adress.

Note that you must
delete ptr;
by hand to return its underlying memory.
ptr itself is not deleted, it just points to a deleted variable.

int a;
is different. a doesn't need new and it's deleted when it goes out of {scope}.
Use scope deletion whereever possible. It's faster and safer.

Answer 2

pointers should hold the address of other variables.
try this:

int main(){
int *ptr, a;

a = 5;
ptr = &a;

cout << *ptr;
return 0;
}

Answer 3

How does a program crush? And what is it crushing?

Answer 4

By program crush , i mean runtime error