What is the difference between CreateProcess and CreateProcessA ?

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What is the difference between CreateProcess and CreateProcessA ?

Hi, what is the difference between CreateProcess and CreateProcessA, also are there any alternatives to these in VC++ 2008 ?

I have also a problem, that i use the CreateProcessA function, this works well in one system but fails in other systems.

Also when i use CreateProcess i get the error cannot convert 2 parameter from 'CHAR[40]' to 'LPWSTR' i am in unicode mode

+2 A:

CreateProcess is identical to either CreateProcessA ("ANSI") or to CreateProcessW ("Wide characters"), depending on whether you're compiling your code without or with the unicode option enabled.

The difference is whether the string which you pass as a parameter should be an ANSI (8-bit character) or a unicode (16-bit character) string.

There are also alternatives, like ShellExecuteEx.

ChrisW 2010-06-17 10:58:57

I have also a problem, that i use the CreateProcessA function, this works well in one system but fails in other systems. what may be reason. are there any other functions ?

rajivpradeep 2010-06-17 11:01:49

@rajivpradeep - "what may be reason" What is the value returned by the `GetLastError()` function immedately after the call to `CreateProcessA` fails?

ChrisW 2010-06-17 11:05:35

A is for "ANSI" but otherwise the answer is corret (ASCII is a 7 bit only character set)

Frank Bollack 2010-06-17 11:06:44

Note that the A in CreateProcessA stands for [ANSI](http://en.wikipedia.org/wiki/Windows-1252), not for [ASCII](http://en.wikipedia.org/wiki/Ascii). Similar, but not the same.

0xA3 2010-06-17 11:07:17

A corollary of this answer is: Only use `CreateProcess` and don't use `CreateProcessA` or `CreateProcessW` directly in your code.

0xA3 2010-06-17 11:09:25

@rajivpradeep@ try using the `CreateProcess` function instead.

Frank Bollack 2010-06-17 11:10:03

@Frank I don't see that making a difference, since any distinction between the two would be determined at compile-time not at run-time.

ChrisW 2010-06-17 11:12:07

@Chris: if you refer to my last comment, you are right, it is a compile time issue and the compiler will most likely point you to the solution.

Frank Bollack 2010-06-17 11:23:36

I am using CreatProcess now, but an error is showing that cannot convert 'char [40]' to 'LPWSTR', i am using unicode mode

rajivpradeep 2010-06-17 11:27:51

Using CreateProcess in unicode mode is equivalent to using CreateProcessW. It requires an array of `wchar_t` instead of an array of `char`, for example `L"foo.exe"` instead of `"foo.exe"` (note the extra `L` to specify a wide-string literal). See also the `TCHAR` macro.

ChrisW 2010-06-17 11:30:52

+2 A:

First, CreateProcess is a macro that switches between CreateProcessA and CreateProcessW, which take strings in ANSI or Unicode, respectively. This depends on your project build settings (the character set project property), Unicode vs Multi-Byte. Generally, you want things to be in Unicode, as this allows for globalization and adds the option of allowing more supported languages.

The complaint in converting from char to LPCWSTR shows that it's expecting a type of WSTR, or wide string, or unicode string. A workaround is to declare your chars using the _T("blahblah") macro.

Stefan Valianu 2010-06-17 14:21:51

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What is the difference between CreateProcess and CreateProcessA ?

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