error by creating process - c++

Question

hello i want to get startet with programming with WIN32, therefore i wrote a programm that creates a process but in the line of code where i create the process the programm gets an error an dosn't work (abend). i don't know if the code in programm 1 is wrong or the code in the second programm that should be created by the first. ( I don't know if the code in the first programm after "createprocess" is right because i didn't get further with debugging, because in this line i get the error.(i tested it without the cout,waitforobject and close handle but i didn't work either )).
First Programm:
#include <iostream>
#include <windows.h>
#include <string>
using namespace std;
void main()
{
bool ret;
bool retwait;
STARTUPINFO startupinfo;
GetStartupInfo (&startupinfo);
PROCESS_INFORMATION pro2info;
ret = CreateProcess(NULL, L"D:\\betriebssystemePRA1PRO2.exe", NULL, NULL, false, CREATE_NEW_CONSOLE, NULL,
NULL, &startupinfo, &pro2info);
cout<<"hProcess: "<<pro2info.hProcess<<endl;
cout<<"dwProcessId: "<<pro2info.dwProcessId <<endl;
retwait= WaitForSingleObject (pro2info.hProcess, 100);
retwait= WaitForSingleObject (pro2info.hProcess, 100);
CloseHandle (pro2info.hProcess);//prozesshandle schließen
retwait= WaitForSingleObject (pro2info.hProcess, 100);
ExitProcess(0);
}
Seconde Programm:
#include <iostream>
#include <windows.h>
#include <string>
using namespace std;
void main()
{
int b;
b=GetCurrentProcessId();
cout<<b<<endl;
cout<<"Druecken Sie Enter zum Beenden"<<endl;
cin.get();
//warten bis Benutzer bestätigt
Sleep (700);
ExitProcess(0);
cout<<"test";
}
Thanks in advance

Answer 1

Notice the type of the lpCommandLine parameter to CreateProcess -- it is LPTSTR, not LPCTSTR, i.e. it is not const.
This means that CreateProcess reserves the right to actually modify the contents of lpCommandLine. However, you have provided a pointer to a string literal as parameter, and string literals are immutable (they come from your program's read-only data segment and attempts to alter them will typically result in an access violation error.)
To fix this, simply change your code not to use an immutable string literal:
wchar_t wcsCommandLine[] = L"D:\\betriebssystemePRA1PRO2.exe";
ret = CreateProcess(NULL, wcsCommandLine, NULL, NULL, ...
Interestingly enough, CreateProcessW (UNICODE) attempts to write to lpCommandLine whereas CreateProcessA (ANSI) does not, and surprise -- your first program is built as UNICODE (were you to build it as ANSI it would work out of the box, at least on Windows XP.)
I can confirm that, with the above modification, your code works.
Also note that:
unless you need to specify D:\\betriebssystemePRA1PRO2.exe's window title, position etc. you do not need to supply a STARTUPINFO structure at all, you can simply pass lpStartupInfo as NULL and a default will be used
you should not be calling WaitForSingleObject on a closed handle

Answer 2

You must set the size of the startupinfo struct:
startupinfo.cb = sizeof(startupinfo);
Maybe this is why CreateProcess is failing.
And by the way - why are you calling GetStartupInfo? You should just zero out the memory of startupinfo (besides setting the size as mentioned above).
See an example here.