स्टैक ओवरफ्लो के साथ Björn Straustrup उत्तर टॉप 5 C ++ प्रश्न

नोट: यह सवाल नंबर 1 है जिसे सभी समय के स्टैक ओवरफ्लो पर सबसे अधिक वोट मिले।

    32995 
          125944 

     18610 
          133304 

     17942 
          107858 

void run(vector<int>& v, const string& label)
{
    auto t0 = system_clock::now();
    sort(v.begin(), v.end());
    auto t1 = system_clock::now();
    cout << label 
         << duration_cast<microseconds>(t1 — t0).count() 
         << " milliseconds\n";
}

void tst()
{
    vector<int> v(1'000'000);
    iota(v.begin(), v.end(), 0);
    run(v, "already sorted ");
    std::shuffle(v.begin(), v.end(), std::mt19937{ std::random_device{}() });
    run(v, "shuffled    ");
}

if (p-->m == 0) f(p);

int p = 2;
int m = 0;
if (p-->m == 0) f(p);

if ((p--) > m == 0) f(p);

int x = 7;
int* p1 = &x;
int* p2 = new int{9};

*p1 = 9;       // write through p1
int y = *p2;   // read through p2

p1 = p2;       //  p1  p2    int   9
*p2 = 99;      //  99  p2
int z = *p1;   //   p1, z  99 (  9)

int x = 7;
int& r1 = x;
int& r2 = *new int{9};

r1 = 9;        //   r1
int y = r2;    //   r2

r1 = r2;       //  p1  p2     9
r1 = 99;       //  99  r1
int z = r2;    //   r2, z  9 (  99)

void f(int* p)

{
    if (p == nullptr) return;
    // ...
}

void g(int& r)
{
    // ...
}

int x = 7;
f(&x);
g(x);

vector<string> split(const string& s)
{
    stringstream ss(s);
    vector<string> words;
    for (string w; ss>>w; ) words.push_back(w);
    return words;
}

auto words = split("here is a simple example");   // five words
for (auto& w : words) cout << w << '\n';

for (auto& w : split("here is a simple example")) cout << w << '\n';

template<typename Delim>
string get_word(istream& ss, Delim d)
{
    string word;
    for (char ch; ss.get(ch); )    //  
        if (!d(ch)) {
            word.push_back(ch);
            break;
        }
    for (char ch; ss.get(ch); )    //  
        if (!d(ch))
            word.push_back(ch);
        else
            break;
    return word;
}

vector<string> split(const string& s, const string& delim)
{
    stringstream ss(s);
    auto del = [&](char ch) { for (auto x : delim) if (x == ch) return true; return false; };

    vector<string> words;
    for (string w; (w = get_word(ss, del))!= ""; ) words.push_back(w);
    return words;
}

auto words = split("Now! Here is something different; or is it? ", "!.,;? ");
for (auto& w : words) cout << w << '\n';