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Kernel: C++17

C++ 17 in CoCalc / Ubuntu 20.04

Lambda-capture not only by reference, but also by value!

struct MyObj {
  int value{ 123 };
  auto getValueCopy() {
    return [*this] { return value; };
  }
  auto getValueRef() {
    return [this] { return value; };
  }
};

MyObj mo;
auto valueCopy = mo.getValueCopy();
auto valueRef = mo.getValueRef();

mo.value = 31;
valueCopy(); // 123
123
valueRef(); // 321
31

Range-based for loop

std::array<int, 5> a{ 1, 2, 3, 4, 5 };
for (int& x : a)  {
    x = 2*x + 1;
}

#include <iostream>

for(auto const& x: a) {
  std::cout << x << " ";
}
3 5 7 9 11

for loop

int i;
for (i = 0; i < 10; i++) {
    std::cout << "i=" << i << "\n";
}
int x = i;
std::cout << x;
i=0 i=1 i=2 i=3 i=4 i=5 i=6 i=7 i=8 i=9 10

cin text input

int y;
std::cin >> y;
2 * y + 1
17