error C2228: left of '.push_back' must have class/struct/union

Question

Just started to learn vector, but I got this error from VC++2010 and stuck there, help please....

"error C2228: left of '.push_back' must have class/struct/union"

#include <vector>
#include <iostream>
#include <limits>

using namespace std;

int main()
{
    vector<double> myVector();
    double temp = 30.0;
    myVector.push_back(temp);   //this line makes error ?? why??

    return 0;
}

Smells pretty vexing to me. – Brian Cain Jul 23 '13 at 03:22 — Brian Cain, Jul 23 '13 at 03:22
Welcome to world of vexing parsing in c++ – shivakumar Jul 23 '13 at 03:28 — shivakumar, Jul 23 '13 at 03:28

score 7 · Accepted Answer · answered Jul 23 '13 at 03:23

7

vector<double> myVector();

this line looks like a forward declaration of a function returning vector.

It should be just

vector<double> myVector;

answered Jul 23 '13 at 03:23

Karadur

1,226
9
16

score 2 · Answer 2 · edited May 23 '17 at 12:13

Your problem is here, you are declaring a function not a vector, this is known as most vexing parse. What you currently have is being interpreted as a forward declaration of a function that takes no arguments that returns a vector<double>:

vector<double> myVector();
                       ^^

if you just want to use the default constructor, it needs to be:

vector<double> myVector ;

Unrelated to your current issue, I would advise against using namespace std;. I realize it is everywhere and it saves some typing but in the long run it will cause you problems.

score 2 · Answer 3 · answered Jul 23 '13 at 03:24

2

This sentence is wrong:

vector<double> myVector();

or the complier will consider the myVector a function which return a value of vector!!

you should define a vector like this:

vector<double> myVector

answered Jul 23 '13 at 03:24

minicaptain

1,196
9
16

That simple but I do not realize it, thx.... – liau Jul 23 '13 at 03:33

error C2228: left of '.push_back' must have class/struct/union

3 Answers3