代码是C还是C++？

Question

I know the code below used to be C, however, I wrote it in visual studio 2008 as a c++ program and it works fine (it is saved as C++). However, the program is in C code, correct? (or is it?).

So, when I tried to compile it inside Visual Studio as C (Go to-> Properties of file -> c/c++ ->Advanced -> Compile as -> changed it to 'Compile as C code') I then get many errors, the main of which it does not recognize the LPSTR type. So, I guess my question is: is it C or C++ code and if it is C, why did it not work when I changed it to compile C code?

#include "stdafx.h"
#include <stdio.h>
#include <windows.h>
#include <strsafe.h>
#include <direct.h>
#include <string.h>
#include <conio.h>

int main(VOID)
{
    STARTUPINFO si;
    PROCESS_INFORMATION pi;

    //allocate memory
    ZeroMemory(&si, sizeof(si));
    si.cb = sizeof(si);
    ZeroMemory(&pi, sizeof(pi));


    //create child process
    if (!CreateProcess(NULL,
                L"C:\\Windows\\Notepad.exe",
                NULL,
                NULL,
                FALSE,
                0,
                NULL,
                NULL,
                &si,
                &pi))
    {
        fprintf(stderr, "create process failed");

        return -1;
    }

    //parent waits for child to complete
    WaitForSingleObject(pi.hProcess, INFINITE);

    printf("Child Complete");

    //close handle
    CloseHandle(pi.hProcess);
    CloseHandle(pi.hthread);

}  

Answer 1

It compiles cleanly as C . The only error is triggered by CloseHandle(pi.hthread) , since it's not a member of PROCESS_INFORMATION . You're looking for hThread (capital T).

Answer 2

It's C. But most C++ compilers are capable compiling C code. The header conio.h is not a part of standard C so you may want to avoid that.

LPSTR is defined in windows.h and since you have included it, it shouldn't give any error. It is typedef'ed:

typedef char* PSTR, *LPSTR; 

For other typedef'ed variables in your code, you have to check if their headers. Try including Winbase.h

Answer 3

From what you give we can't see if it is valid C because you are using non-standard headers and macros. But I can imagine that there could be macro definitions that turns this into C code.

If it is C, it is not so good one, and not so good one for C++ either. Both languages have their way of initializing variables, but your code uses none of them. In particular in C (and for PODs in C++) there are initializers for initializing variables. Supposing that both ugly macros here expand to types:

STARTUPINFO si = { 0 };
PROCESS_INFORMATION pi = { 0 };

of if you have a C99 compliant compiler the first would even better be

STARTUPINFO si = { .cb = sizeof si };

If for some reason you'd need a function to zero out a whole block of memory, better use the standard function memset for that. But if you use the correct initializers in C (or constructors in C++) you should rarely need that explicitly.

Answer 4

every c code is a valid c++ code. but its not the other way around. So if you want to use OS api's which are c++ then you should compile it as c++.