error: ‘i’ does not name a type with auto [duplica

Question

This question already has answers here:

How do I enable C++11 in gcc? (3 answers)

Closed 4 years ago.

I am new to C++,here is my program

#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <functional>  

int main(){

static const double arr[] = {16.0,2.2,77.5,29.0,24.0};
std::vector<double> vec (arr, arr + sizeof(arr) / sizeof(arr[0]) );

std::transform(vec.begin(), vec.end(), vec.begin(),bind2nd(std::minus<double>(), 3.0)); 

for (auto i = vec.begin(); i != vec.end(); ++i)
    std::cout << *i << ' ';

}

When I try to compile with g++ p1.cpp -o p1

p1.cpp: In function ‘int main()’:
p1.cpp:14:11: error: ‘i’ does not name a type
 for (auto i = vec.begin(); i != vec.end(); ++i)

I know that there more ways to print the vector,but why is this not working?

Answer 1

You should try with -std=c++11 . Works fine after that.

./p1
13 -0.8 74.5 26 21 

Answer 2

Or if your compiler does not support c++11, use std::vector<double>::iterator instead of auto.