CODEWITHSUNDEEP
c++
kroosha44
kroosha44

Reputation: 21

Why isn't my GetProcessID function compiling in VS?

so for some reason my GetProcessID function is working in one project (no errors when compiling the source) but recently I just started a new project and now I am getting the error

'int strcmp(const char *,const char *)': cannot convert argument 1 from 'WCHAR [260]' to 'const char *'

But why am I even getting this cannot convert from WCHAR to const char * error? If I hover over p32.szExeFile szExeFile is type CHAR [260] not WCHAR. Also, I went into property pages and selected Use Multi-Byte Character Set. Even if I change std::string processName parameter to 

const char *processName

or

char *processName 

wchar_t *processName

I still get the same error.

So my question is this: Why is it that my GetProcessID function works in another project without any compilation errors but when I try to use this same function in a brand new project I get an error?

  DWORD GetProcessID(std::string processName)
    {
        PROCESSENTRY32 pe32;
        pe32.dwSize = sizeof(PROCESSENTRY32);

        HANDLE hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
        if (hSnapshot == INVALID_HANDLE_VALUE)
        {
            std::cout << "CreateToolhelp32Snapshot() (of processes)" << std::endl;
            std::cin.get();
            return 0;
        }

        if (!Process32First(hSnapshot, &pe32))
        {
            CloseHandle(hSnapshot);
            std::cout << "The first entry of the process list wasn't copied to the buffer." << std::endl;
            std::cin.get();
            return 0;
        }

        while (Process32Next(hSnapshot, &pe32))
        {
            if (strcmp(pe32.szExeFile, processName.c_str()) == 0)
            {
                CloseHandle(hSnapshot);
                return pe32.th32ProcessID;
            }
        }

        CloseHandle(hSnapshot);
        return 0;
    }

    int main()
    {
        DWORD dwProcessID = NULL;
        while (dwProcessID == NULL)
        {
            dwProcessID = GetProcessID("proc.exe");
        }

        std::cout << "Found PID " << dwProcessID << std::endl;
        std::cin.get();
        return 0;
    }

Upvotes: 2

Views: 362

Answers (1)

catnip
catnip

Reputation: 25388

The failing project is compiled as Unicode. When you do that, strings in PROCESSENTRY32 are defined as WCHAR [] rather than char [].

One solution would be to explicitly code PROCESSENTRY32A (and Process32FirstA / Process32NextA), although Unicode strings are better able to represent non-ASCII characters.

Upvotes: 4

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