C++ TlHelp32.h program closes after being written to - c++

Question

I was learning how to interact with processes from a channel called "null". I wrote his program and tried to understand how everything worked. But when i executed it the wpm function did work but then the target program immediately closed after it incremented the same variable I was writing to.
Anyways here's the code.
#include <iostream>
#include <Windows.h>
#include <TlHelp32.h>
HANDLE hProc = NULL;
DWORD ProcId;
bool attatchProc(const char* ProcName)
{
PROCESSENTRY32 procEntry;
procEntry.dwSize = sizeof(PROCESSENTRY32);
auto hProcSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if (hProcSnap == INVALID_HANDLE_VALUE)
return false;
while (Process32Next(hProcSnap, &procEntry)) {
std::cout << procEntry.szExeFile << std::endl;
if (!strcmp(ProcName, procEntry.szExeFile)) {
std::cout << "Process Found!\n Heres the Process ID" << procEntry.th32ProcessID << std::endl;
ProcId = procEntry.th32ProcessID;
hProc = OpenProcess(PROCESS_ALL_ACCESS, false, ProcId);
if (hProc == NULL)
std::cout << "Sike you thought lmao" << std::endl;
CloseHandle(hProcSnap);
return true;
}
}
std::cout << "Process not found or other issue";
}
template <class DataType>
void wpm(DataType VarToWrite, DWORD addressToWrite)
{
WriteProcessMemory(hProc, (PVOID)addressToWrite, &VarToWrite, sizeof(DataType), 0);
}
int main()
{
DWORD memAddr = 0x012FF848;
attatchProc((char*)"Testing.exe");
while (1)
{
wpm<int>(68, memAddr);
}
}

Answer 1

You are not using Process32First to get the first entry in the snapshot. Microsoft Docs has a tutorial on how to do it correctly here
If you use the tutorial you can come up with your own version like mine, which includes exactly what you need and nothing else. I use TCHAR in this example so you can either include tchar.h or you can change it to match your coding style.
#include
DWORD GetProcId(const TCHAR* procName)
{
DWORD procId = 0;
HANDLE hSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if (hSnap != INVALID_HANDLE_VALUE)
{
PROCESSENTRY32 procEntry;
procEntry.dwSize = sizeof(procEntry);
if (Process32First(hSnap, &procEntry))
{
do
{
if (!_tcsicmp(procEntry.szExeFile, procName))
{
procId = procEntry.th32ProcessID;
break;
}
} while (Process32Next(hSnap, &procEntry));
}
}
CloseHandle(hSnap);
return procId;
}
After calling this function you would check if the return is nonzero and then call OpenProcess() using the process id and the memory access permissions you require. If the process handle is nonzero you may then continue to write to the process memory. If you write to the incorrect memory address you will crash the program, so ensure you have the correct address by using the Visual Studio Debugger and comparing what you see against what you see in the target process using another debugger like Cheat Engine.