Accessing memory locations in C/C++

I was wondering something about C/C++.

I used java for a while but now i'm going into C/C++...I love the freedom associated with the language...one can access all sorts of things that was protected or disabled in java...real programming freedom.

However, I was wondering if I could access memory locations and print out the contents for a test on memory accessing or will that work?

I was trying

#include <iostream.h>

int main()
{
int a; //create the variable
int *aPtr; //create pointer to memory location

aPtr = &a;
cout << aPtr << endl;

return 0;
}

that prints out the memory locatin in hex

can I explicitly give the pointer a memory location from the program or will the OS give me an error message?

I think it's all interesting, things one couldn't do in Java, more control over what you're doing.

Thanks for any help

nahdoic

MoonHawk are you in case2 in DCU? Cos we are doing this stuff in c++ now ... and we only did java last year. Sounds like you are

Gavin

you should use the redbrick boards aodhan

get them to renew your account.

Gav

Typedef

Originally posted by MoonHawk
I was wondering something about C/C++.

I used java for a while but now i'm going into C/C++...I love the freedom associated with the language...one can access all sorts of things that was protected or disabled in java...real programming freedom.

However, I was wondering if I could access memory locations and print out the contents for a test on memory accessing or will that work?

I was trying

#include <iostream.h>

int main()
{
int a; //create the variable
int *aPtr; //create pointer to memory location

aPtr = &a;
cout << aPtr << endl;

return 0;
}

that prints out the memory locatin in hex

can I explicitly give the pointer a memory location from the program or will the OS give me an error message?

I think it's all interesting, things one couldn't do in Java, more control over what you're doing.

Thanks for any help

You might try something like

cout<<aptr<<endl; //giving you say 0x100

aptr=(long*)&aptr+(or)-the number you would like it to equal say 102
aptr=(long*)&aptr+2;
cout<<aptr<<endl;
or something similar possibly.

Zab

You could try somthing along the lines of this:

#include <iostream>

using namespace std;

void main(){

int val = 100;
int *ptr = &val;

// Note that we are printing out the values as integers, because the
// pointer is declared to be pointing at an integer. You could write your
// own code to print it in some other form
cout << "Address " << ptr << endl;
cout << "Has value " << *ptr << endl << endl;

// This adds 4 to the pointer ( assuming 64bit ints )
// ( pointer arithmetic multiplys by the size of the type of the pointer
// , in this case we defined ptr to be a pointer to an int, so adding one
// to it will in fact add 4 becase int's as 4 bytes long )
ptr++;
cout << "Address " << ptr << endl;
cout << "Has value " << *ptr << endl << endl;

// This adds 8 to the pointer ( assuming 64bit ints )
ptr+=2;
cout << "Address " << ptr << endl;
cout << "Has value " << *ptr << endl << endl;

// Sets the pointer to point at a specific address
// A random address may not belong to the programs memory space
// and so may generate an access violation
ptr = (int*)0x130000;
cout << "Address " << ptr << endl;
cout << "Has value " << *ptr << endl << endl;

}

MoonHawk are you in case2 in DCU? Cos we are doing this stuff in c++ now ... and we only did java last year.

you should use the redbrick boards aodhan

Aha! They've found me out!! NOOOOOO!
Seriously, that's cool to know fellow DCU people are out there, using these boards! Nice one.
Actually I still use Redbrick! Haven't kicked me off, I renewed the account!

Zab and Typedef, thanks for the help, useful as always