CODEWITHSUNDEEP
c++constructor
user1409254
user1409254

Reputation: 49

c++: Why is constructor called here

I have a deep copy method in a custom container myCont. I have an instance of an unsorted container that I need to sort and dump. I create a temp container with sorted flag on, call the copy method and Dump. But the app code below creates an empty container and passes that rather than my (loaded) container. Need help figuring out what is going on here. Thanks in advance

void myCont::Copy(const myCont& srcCont)
{
    // code to deep copy from srcCont
}

App Code:

fn(x, z, z) {
    myCont dC();
    dC.setSorted(true);
    dC.Copy(sC);
    dC.DumpCont();
}

Assembly:

myCont dC();   
0000000140323068  mov         dl,1  
000000014032306A  lea         rcx,[dC]  
0000000140323072  call        myCont::myCont (0141E1A01Ah)  
0000000140323077  nop   
        dSet.Copy(sC);
0000000140323078  cmp         qword ptr [sC],0  
0000000140323081  je          CR::evaluate+6FDh (014032308Dh)  
0000000140323083  mov         byte ptr [rsp+0C2h],1  
000000014032308B  jmp         CR::evaluate+705h (0140323095h)  
000000014032308D  mov         byte ptr [rsp+0C2h],0  
0000000140323095  movzx       edx,byte ptr [rsp+0C2h]  
000000014032309D  lea         rcx,[rsp+6F0h]  
00000001403230A5  call        myCont::myCont (0141E1A01Ah)  <-WHY THIS CTROL CALL ????????????
00000001403230AA  nop  
00000001403230AB  lea         rdx,[rsp+6F0h]  
00000001403230B3  lea         rcx,[dC]  
00000001403230BB  call        myCont::Copy (0141E1A188h)  
00000001403230C0  nop  
00000001403230C1  lea         rcx,[rsp+6F0h]  
00000001403230C9  call        myCont::~my Cont(0140009280h)  
      dC.DumpCont();
00000001403230CE  lea         rcx,[dC] 
00000001403230D6  call        myCont::DumpCont(014019B240h)

Upvotes: 0

Views: 64

Answers (2)

Michael Burr
Michael Burr

Reputation: 340208

From the little bit of code you posted:

void myCont::Copy(const myCont& srcCont)
{
    // code to deep copy from srcCont
}

this indicates that myCont::Copy() doesn't return a new myCont object and it can't modify the srcCont object. So it's not clear what the Copy() function is actually supposed to be doing.

Also, myCont dC(); is an instance of the most vexing parse - it's a nop.

Upvotes: 1

Rob L
Rob L

Reputation: 2430

This is not a complete example, but since you provided the assembly, I think I can tell what is going on.

sC is converting to a bool (cmp to zero, then set either a one or a zero). You must have an implicit constructor in the myCont class that can convert from a bool. sC is apparently not of type myCont. Is sC a myCont * by any chance?

Upvotes: 2

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