Header file <intrin.h>

The __debugbreak compiler intrinsic, similar to DebugBreak, is a portable Win32 way to cause a breakpoint.

Note:
When compiling with /clr, a function containing __debugbreak will be compiled to MSIL. asm int 3 causes a function to be compiled to native. For more information, see __asm.

For example:

main() {
   __debugbreak();
}

is similar to:

main() {
   __asm {
      int 3
   }
}

on an x86 computer.

This routine is only available as an intrinsic.

Reference