vector of structs

[oceanx]

Hi everybody,

the "insert" function of a vector copies the param? or just refers to
the structure?

for example:

typedef struct {
int a;
...
} structType;

void f ( vector <structType> & v){
stryctType xx;
xx.a = 10;
v.add (xx); // it really *copies* xx in v... isn't it?
}

int main(){

f (vect);
cout << vect[0].a;
}


it works, but... is it correct?

thanks,
Major

 

[Chris Theis]

Hi everybody,

the "insert" function of a vector copies the param? or just refers to
the structure?

for example:

typedef struct {
int a;
...
} structType;

void f ( vector <structType> & v){
stryctType xx;
xx.a = 10;
v.add (xx); // it really *copies* xx in v... isn't it?
}

int main(){

f (vect);
cout << vect[0].a;
}


it works, but... is it correct?

Sorry, but the program above neither works/compiles nor is it correct. Among
other things there is no member function add for the class vector, so I
guess you meant something like insert or push_back. These functions do
create a copy which is placed in the container and thus, there is the
requirement that those objects stored in a standard container must be copy
constructible.

HTH
Chris

 

[usr.root]

are sure that's ok,i found no add() in the monber function of vector of
stl

 

[Mateusz Loskot]

Hi everybody,

the "insert" function of a vector copies the param? or just refers to
the structure?

Copy of structure will be inserted.
I'd recommend you to read this great book by Nicolai M. Josuttis:
http://www.josuttis.com/libbook/index.html

Recommended chapter with explanation is 6.1 "Common Container Abilities
and Operations".

Shortly, ALL STL containers are based on semantic of value not
reference, so they operate on copies internally.

 

[oceanx]

Copy of structure will be inserted. [cut]
Shortly, ALL STL containers are based on semantic of value not
reference, so they operate on copies internally.

cheers!
I have "Borland C++: The Complete Reference" by Schildt, but it isn't
really clear on this point...

 

[oceanx]

Sorry, but the program above neither works/compiles nor is it correct. Among
other things there is no member function add for the class vector, so I
guess you meant something like insert or push_back. These functions do
create a copy which is placed in the container and thus, there is the
requirement that those objects stored in a standard container must be copy
constructible.

sorry, my fault (yes, I meant something like insert or push_back)...
when I wrote I was far from my compiler :-(

thanks a lot,

Major

 

[oceanx]

are sure that's ok,i found no add() in the monber function of vector of
stl

my mistake, sorry!

 

[deane_gavin]

cheers!

I have "Borland C++: The Complete Reference" by Schildt, but it isn't
really clear on this point...

Schildt seems to be an unfortunate choice of author, although that
particular title isn't reviewed

http://www.accu.org/bookreviews/public/reviews/0au/s.htm

Get yourself a copy of Accelerated C++

http://www.acceleratedcpp.com/

Gavin Deane