How to check whether a program is debugged

How to detect Program Debugging is actually very easy, just a few lines Code That's it. It is often used in anti-cracking software, but it is ineffective for some debuggers (such as the improved ollydbg-ollyice ).
Below is the C + ASM code. You can try it.
# Include <stdio. h>
# Include <conio. h>
Int isdebugged ()
{
_ ASM
{
MoV eax, FS: [30 h] // get the address of the process environment block corresponding to the thread environment Block
Movzx eax, byte PTR [eax + 2 H] // obtain the value of the bebingdebugged flag
Or Al, Al // test the value of the bebingdebugged flag
JZ flag1
MoV eax, 1
JMP end
Flag1:
MoV eax, 0 // The XOR eax and eax statements are recommended.
End:
}
}

Int main ()
{
If (isdebugged ())
{
Printf ("with a debugger! /N ");
}
Else
{
Printf ("No debugger! /N ");
}
Getch ();
Return 0;
}