Why doesn't the compiler recognize sort with a single argument?

Question

I am learning C++ from Bjarne Stroustrup's Programming Principles and Practice with C++. I copied the code and the compiler found an error (E0304) with the usage of sort(words).

#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>

using namespace std;

inline void keep_window_open() { char ch; cin >> ch; }

int main() {
    vector<string> words;
    for (string temp; cin >> temp; )
        words.push_back(temp);
    cout << " Word count : " << words.size() << ' \n ';
    sort(words);
    for (int i = 0; i < words.size(); ++i)
        if (i == 0 || words[i - 1] != words[i])
            cout << words[i] << "\n";
}

Is this an error in the book, or am I doing something wrong?

Answer 1

The book explains at the beginning that you are supposed to include a file named std_lib_facilities.h coming with the book. It can also be downloaded from the author's website here.

This is a non-standard file used in the book to simplify some constructs for introducing the language.

This file defines a function sort that can be called directly on a container. The std::sort function from the standard library does not allow for that.

So add

#include "std_lib_facilities.h"

at the beginning. (And I think you are also not supposed to add any of the standard library headers and using namespace std; yourself either. I can't check the book right now though.)

Answer 2

Until C++20 the standard library didn't provide such a function. You can use std::sort like this:

std::sort(words.begin(), words.end());

However, since this can be annoying, C++20 provides std::ranges::sort, that does what you want:

std::ranges::sort(words);

To use this function you have to use a compiler that supports C++20.

Answer 3

sort arguments are have to be iterators. Replace

sort(words);

by

sort(words.begin(), words.end());