CODEWITHSUNDEEP
c++pointers
Cường Đặng Cao
Cường Đặng Cao

Reputation: 47

Assign address of number to a pointer

int *n=(int *)5;//Valid
cout<<*n;//Invalid

Why pointer n can point to an address although 5 is not a memory location. Why I can not print out the screen the value of n.

Upvotes: 1

Views: 149

Answers (2)

Mad Physicist
Mad Physicist

Reputation: 114230

Short answer: because the value of n is n. *n is the value at n: i.e., what it's pointing to.

If you want n to point to the value 5 rather than the address 5, you have to make it do so:

int x = 5;
int* n = &x;

Now n is the address of a stack location that has 5 as its value.

Upvotes: 1

Shane Reilly
Shane Reilly

Reputation: 251

You are attempting to dereference memory address 0x5, which is probably restricted memory.

int *n=(int *)5;

You are casting the integer literal 5 as an int*. What that means is you are saying 0x5 is an address. When attempting to dereference that pointer with *n, you will get an error.

Instead, you would need to do something like:

int five = 5;
int *n = &five;
cout << *n;

Don't use (int *), use the address-of operator &. Also keep in mind you cannot take the address of a literal other than string literals.

Upvotes: 3

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