Why are functions in

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• What is “Argument-Dependent Lookup” (aka ADL, or “Koenig Lookup”)? 4 answers

I have the following basic code that creates a vector and tries finding an element in it. I noticed that you don't need to specify the std:: namespace to call find and was wondering if there was any particular reason the functions in <algorithm> are not wrapped in namespace std? I ask because I was recently writing a find method and encountered an ambitious compiler error.

Isn't the whole point of namespaces to avoid this sort of thing?

#include <iostream>
#include <vector>
#include <algorithm>

using std::cout;    using std::endl;
using std::vector;  using std::string;


int main() {
    std::vector<int> v = {1,5,6,9,3,4};
    auto i = find(v.begin(), v.end(), 3);       // why does this work without std:: at the beginning
    cout << "Output: " << *i << endl;
}