is push_back() a overloaded function ?

**blue_gene** · 05-01-2004

i am so sorry. its working. may be that was a bad copy.i checked again. this time its working.

did you notice push_back() is taking a pointer p . but when i usued pointer p in my original code push_back() gave me an error. thats why i wrote //illegal.

what push_back() actually demands ? does it demand pointer and argument both . then i have to call it a overloaded function !!

its really a peculiar behaviour of push_back().....

i may be wrong somewhere.....

**alphaoide** · 05-01-2004

push_back() takes any type of parameter which matches the vector declaration.

Code:

vector<TYPE> v;
void push_back( const TYPE &val );

if you create a vector of int then you push back an int, if it's a float then push_back float, if it's MyObject then push_back MyObject, if it's a container for pointers to MyObject then push_back a pointer to MyObject

**axon** · 05-01-2004

it works here as well...although g++ is giving a warning with -Wall flag

**blue_gene** · 05-01-2004

>>if you create a vector of int then you push back an int, if it's a float then push_back float, if it's MyObject then push_back MyObject, if it's a container for pointers to MyObject then push_back a pointer to MyObject

-----ok. i see ...its the matter then . thanks for the explanation.
its ok. i understand about the usage of push_back() function. i understand how to handle it.

if you dont mind can i ask one more confusion.

see your definition ......
vector<TYPE> v;
void push_back( const TYPE &val );

now replace TYPE by int*

vector<int*> v;
void push_back( const int* &val ); => void push_back(cont int val) // so push_back now demand simple argument !! bcoz * & == Doomed.

sorry for the last silly and bad mathematical calculation.

anyway.....i understand how to use push_back() now. your rule is ok.

thanks

**skorman00** · 05-01-2004

a pointer reference is perfectly legal. I was once working with a linked list somebody made with a traverse function that took a function pointer as its parameter. The function pointer had to take in a Type &. So when I made a linked list of CObject * 's, I had to make a function like this to pass to Traverse:

Code:

bool Func(CObject * & obj)
{
}

**Codeplug** · 05-01-2004

Don't confuse pointers with references - they are different.

"const T &" is not a pointer, it's a constant reference to type T.

The reference part (&) says - "don't make a copy and don't call any copy constructors"
The "const" part says - "even though it's a reference, I promise not to modify it"

For most native types, there is very little overhead in making copies.
For class/struct types, the overhead can be large. So all STL containers (that I know of) will only make a single copy of an object when you add that object to the container.

gg

**blue_gene** · 05-01-2004

>>"const T &" is not a pointer, it's a constant reference to type T.
....hmmm.

thanks.....you guys are very helpful and cordial. i understand where i was wrong......i learned a lot. its ok.

**Sang-drax** · 05-02-2004

Originally Posted by JaWiB

Code:

#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<char* > z;
char y[2];
y[0]='a';
y[1]='b';
y[2]='\0';
z.push_back(y);
cout<<z[0]<<endl;
cout<<z[1]<<endl;
}

That won't work as intended.
The first cout will print 'ab', the second is undefined behaviour.

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