Segmentation Fault when Calling Functions

When I run the following code I get a segmentation fault.

Code:

#include <iostream>
using namespace std;

typedef int* IntPointer;

void notsneaky(IntPointer temp);
void sneaky(IntPointer temp);
void sneakybutnotsneaky(IntPointer& temp);

int main()
{
IntPointer p;

	p = new int;
	*p = 77;
	cout<<"Before call to function *p == "
           << *p << endl;
    
    
       notsneaky(p);
    
       cout<<"After call to \"notsneaky\" function *p == "
           << *p << endl;
           
       sneaky(p);
    
       cout<<"After call to \"sneaky\" function *p == "
           << *p << endl;
           
       sneakybutnotsneaky(p);
    
       cout<<"After call to \"sneaky_but_notsneaky\" function *p == "
           << *p << endl;
        
        return 0;
}

void notsneaky(IntPointer temp)
{
      int *ptr;
      *ptr=23;
	temp = ptr;
	cout<<"Inside the function call *temp == "
	    <<*temp<<endl;
}

void sneaky(IntPointer temp)
{
	*temp = 99;
	cout<<"Inside the function call *temp == "
	    <<*temp<<endl;
}

void sneakybutnotsneaky(IntPointer& temp)
{
      int *ptr;
      *ptr=37;
	temp = ptr;
	cout<<"Inside the function call *temp == "
	    <<*temp<<endl;
}

Here is the output:

Code:

thetinman@computer:~/code$ ./a.out
Before call to function *p == 77
Inside the function call *temp == 23
After call to "notsneaky" function *p == 77
Inside the function call *temp == 99
After call to "sneaky" function *p == 99
Segmentation fault

Does anyonone know what is causing this segmentation fault? How should I go about fixing it?

Code:

void notsneaky(IntPointer temp)
{
      int *ptr;
      *ptr=23;

You are attempting to dereference an uninitialized pointer.