Paste a reference vector to Function

[hqt]

I have tested and see that in C++, C++ doesn't auto paste a reference vector to function like array. So, I use a pointer, but it has some problem for below code:

//Purpose: change value of vector in function
void change(vector<int>*v){
    *v[0]=8; //ERROR HERE
     v[0]=8; //ERROR TOO
}
int main(){
    vector<int>v;
    v.push_back(1);
    change(&v);
    cout<<v[0]<<endl;
    return 0;
}

So, who can help me how to paste a reference vector to function, please.

thanks

[Salem]

a) if you passed it by reference, you would save yourself a whole bunch of messy syntax.

b) Try (*v)[0]=8;

[hqt]

Oh, thanks so much. So, this point maybe the weak point of container in C++, that C++ doesn't auto to do that for programmer

[jimblumberg]

Why are you passing by pointer instead of by reference?

#include <iostream>
#include <vector>
using namespace std;

void change(vector<int>& v)
{
   v[0]=8; 
}
 
int main()
{
   vector<int>v;
   v.push_back(1);
   change(v);
   cout<<v[0]<<endl;
   return 0;
}

Jim

[Elysia]

Oh, thanks so much. So, this point maybe the weak point of container in C++, that C++ doesn't auto to do that for programmer

No, arrays are broken in the language since they are the ones that are the exception. Passing an array to a function will actually pass a pointer to its first element, and that without even having to use the address-of operator which you always have to do otherwise!
In fact, using the address-of operator produces a pointer to the array, which is an entirely different concept, and makes things even worse.

Containers fixed this problem. You simply have to pass them by reference, as you would any normal variable.

[iMalc]

I'm still trying to work out what "auto paste a reference vector to function" means.

[manasij7479]

I'm still trying to work out what "auto paste a reference vector to function" means.

Google image search illustrates it...with some interesting results.

[Elysia]

What picture are you trying to imply is a good fit?
My interpretation is that it simply means passing an array to a function. Since the syntax would be

void foo(int array[])

and passing would simply be

foo(array);

There is a high probability that this is indeed what the OP meant.