ReadProcessMemory not working properly with UTF16 string

Question

I'm learning C++ and was messing around with Win32 api, particularly ReadProcessMemory.

So I'm trying to read text from notepad, I've found the address using Cheat Engine. The text is in Windows UTF16

Here's the code I use to read the text:

#include "pch.h"
#include <string>
#include <iostream>
#include <windows.h>

using namespace std;

int main()
{
    LPCVOID Addr = (LPCVOID) 0x1711B91E610;
    HANDLE handle = OpenProcess(PROCESS_ALL_ACCESS, false, 9948);

    u16string data[29];

    if (!handle) {
        exit(0);
    }

    ReadProcessMemory(handle, Addr, &data, 29, 0);
    cout << data << endl;

    cin.get();
}

I was expecting to get this Hello world!zzzzzeeeeeezzzees however, I got this: 00000053A7EFF260

What am I doing wrong? Thank you

edit: tried wcout, also not working

And everytime I run the program, I get a different hex value, what?

Possible duplicate of [How I can print the wchar\_t values to console?](https://stackoverflow.com/questions/2493785/how-i-can-print-the-wchar-t-values-to-console) — GSerg, Apr 07 '19 at 15:24
What do you think `u16string data[29];` does? How does `ReadProcessMemory(handle, Addr, &data, 29, 0);` populate data? — Eljay, Apr 07 '19 at 15:30
@Eljay Well [29] is to declare the length of the string I suppose? As my string is 29 chars — MikeKZ4444, Apr 07 '19 at 15:43
"Well [29] is to declare the length of the string I suppose?" You supose wrong. — n. m. could be an AI, Apr 07 '19 at 16:53

KiKoS · Accepted Answer · 2019-04-07T16:53:03.917

First please check your address twice, the 4th argument of ReadProcessMemory takes the number of bytes to read and in this case each character in your string is 2 bytes wide so you have to pass 2*29=58 as the size and finally don't use C++ string because in this case you need a simple data buffer to copy data to and u16string is a complex object with other attributes and methods.

u16string data[29];

This line doesn't create a string with 29 characters but it creates 29 string objects, so use something like this instead:

wchar_t data[30];
data[29] = L'\0';

Allocating 30 is for the null character that terminates the string.

For printing wide char characters use:

wcout << data << endl;

score 0 · Answer 2 · answered Apr 07 '19 at 18:45

u16string data[29]; is an array of 29 u16string objects, it is not a single u16string with a length of 29 chars, like you think it is.

Also, the nSize parameter of ReadProcessMemory() expects a byte count, not a character count. UTF-16 uses 2-byte characters.

Try this instead:

#include "pch.h"
#include <string>
#include <iostream>
#include <windows.h>
using namespace std;

int main()
{
    LPCVOID Addr = reinterpret_cast<LPVOID>(0x1711B91E610);

    HANDLE handle = OpenProcess(PROCESS_ALL_ACCESS, false, 9948);
    if (!handle) {
        return 0;
    }

    u16string data(29, u'\0');
    // or:
    // u16string data; data.resize(29);

    ReadProcessMemory(handle, Addr, &data[0], 29*sizeof(char16_t), 0);
    wcout << reinterpret_cast<const wchar_t*>(data.c_str()) << endl;

    cin.get();
    return 0;
}

ReadProcessMemory not working properly with UTF16 string

2 Answers2