Initializing list of strings in c++11

Question

I was trying to initialize a list of strings in c++11 using the following code, and its failing with various reasons. The error says that I need to use constructor to initialize the list, should I use something like list<string> s = new list<string> [size] ? What am I missing here?

#include<string>
#include<list>
#include<iostream>
using namespace std;

int main() {
      string s = "Mark";
      list<string> l  {"name of the guy"," is Mark"};
      cout<<s<<endl;
      int size = sizeof(l)/sizeof(l[0]);
      for (int i=0;i<size;i++) {
             cout<<l[i]<<endl;
      }
      return 0;
 }

I/O is

 strtest.cpp:8:47: error: in C++98 ‘l’ must be initialized by constructor, not 
 by ‘{...}’
 list<string> l  {"name of the guy"," is Mark"};

This isn't the problem, but do you really need the extra stuff that `std::endl` does? `'\n'` ends a line. — Pete Becker, Jun 03 '17 at 05:26
To get the number of elements in the list `l`, call `l.size()`. That `sizeof` dance only works for C-style arrays. — Pete Becker, Jun 03 '17 at 05:27
Your error message appears to be telling you that you are building with C++98 not 11 — Alex Zywicki, Jun 03 '17 at 05:28

score 11 · Answer 1 · answered Jun 03 '17 at 05:29

11

You are using a compiler of c++98 instead of c++11.using this if you are using gcc

g++ -std=c++11 -o strtest strtest.cpp

you can replace c++11 with gnu++11

answered Jun 03 '17 at 05:29

K.Juce

253
1
6

Thanks, I hardly realized that I was not using c++11, I guess I was scared at the amount of errors I saw and didn't catch this one – Aparna Chaganti Jun 03 '17 at 05:34

Henri Menke · Answer 2 · 2017-06-03T05:37:47.990

10

List initializers are only available in C++11. To use C++11 you probably have to pass a flag to the compiler. For GCC and Clang this is -std=c++11.

Also, std::list does not provide a subscript operator. You could either use a std::vector as in the other answer or you use a range-based for loop to iterate over the list.

Some more hints:

never do using namespace std;
whitespace is free

#include <string>
#include <list>
#include <iostream>

int main() {
  std::string s = "Mark";
  std::list<std::string> l {"name of the guy"," is Mark"};

  for (auto const& n : l)
    std::cout << n << '\n';
}

edited Jun 03 '17 at 05:37

answered Jun 03 '17 at 05:34

Henri Menke

10,705
1
24
42

why should you never use using namespace std? – Makogan Jun 03 '17 at 05:36
1

@Makogan See the link. – Henri Menke Jun 03 '17 at 05:37

score 0 · Answer 3 · answered Jun 03 '17 at 05:30

0

The biggest problem here is that you are using lists. In C++ lists are doubly linked lists, as such the [] doesn't make any sense. You should be using vectors instead.

I'd try:

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

int main() {
      string s = "Mark";
      vector<string> l = {"name of the guy"," is Mark"};
      cout<<s<<endl;
      for (int i=0;i<l.size();i++) {
             cout<<l[i]<<endl;
      }
      return 0;
 }

instead

EDIT: as others pointed out, make sure you are compiling with c++ 11 and not c++ 98

answered Jun 03 '17 at 05:30

Makogan

8,208
7
44
112

Thanks!, what would be use case for using lists then? Can you please explain only if its not too complex? – Aparna Chaganti Jun 03 '17 at 05:35
Well do you know what a linked list is? – Makogan Jun 03 '17 at 05:35
I do, its just that the term "list" is so straightforward and compelling for me to use it in a "regular" context. I guess I was asking why would some one name a doubly linked list as just "list"? – Aparna Chaganti Jun 03 '17 at 05:37
@AparnaChaganti The answers to the following question should help: [vector vs. list in STL](https://stackoverflow.com/q/2209224/445976) – Blastfurnace Jun 03 '17 at 05:43

score 0 · Answer 4 · answered May 20 '20 at 21:40

0

Well the answer to this problem is to just simply copy the contents of one list into another list hope it helps :)

answered May 20 '20 at 21:40

Aditya Aggarwal

159
1
9

Initializing list of strings in c++11

4 Answers4