CODEWITHSUNDEEP
c++cwindows
user1232138
user1232138

Reputation: 5541

Function without a body

I was analyzing this code from the companion CD rom that comes with the book "Windows via C\C++" and I came across this statement 

m_hSnapshot = CreateToolhelp32Snapshot(dwFlags, dwProcessID);

where dwFlags and dwProcessID are DWORD's

And when I jumped to the defination of this function CreateToolhelp32Snapshot I found this 

HANDLE 
WINAPI
CreateToolhelp32Snapshot(
    DWORD dwFlags,
    DWORD th32ProcessID
    );

How could such a function without a body exist?

I tried to debug the code but the compiler doesn't step into this function, instead it simply steps over the first statement with a value of 0x00000754 stored in m_hSnapshot.

Upvotes: 2

Views: 4517

Answers (6)

JMC
JMC

Reputation: 930

Yeah, that's just a prototype for a function that's defined in an existing Windows DLL (Kernel32.dll)

Upvotes: 0

Hituptony
Hituptony

Reputation: 2860

Its just a function to accept parameters, it is probably used by a method somewhere else, after user initialization. It looks like it is actually just getting a snapshot of the processID to display when you say go into the command prompt and request a process display.

Upvotes: 0

J_D
J_D

Reputation: 3586

The body may be at different places, in a static or dynamic library that you link against for example.

Upvotes: 0

K-ballo
K-ballo

Reputation: 81349

What you see is not a function definition but a declaration. The actual definition is provided by dlls in Windows itself, linked to your executable.

Upvotes: 5

Luchian Grigore
Luchian Grigore

Reputation: 258618

The function has a body, but it's just not visible.

That's just the declaration. If it was visible, Windows would be open source (don't laugh). C++ is a compiled language. Binary files are generated from code, the code itself isn't required to call a function.

Upvotes: 0

NPE
NPE

Reputation: 500457

How could such a function without a body exist?

It doesn't. What you're seeing is just a function prototype. The body is defined elsewhere.

Upvotes: 7

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