centralized performance resources

perf-cpp/scripts/ch5.cc

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+#include <cassert>
+#include <cmath>
+#include <concepts>
+#include <iomanip>
+#include <iostream>
+#include <string>
+#include <string_view>
+
+template <std::integral T>
+T binexp(T base, T exponent, T mod) {
+  assert(mod > 0 && exponent > 0);
+
+  T product{1};
+  T multiplier{base % mod};
+
+  while (exponent > 0) {
+    if ((exponent & 1) != 0) {
+      product = (multiplier * product) % mod;
+    }
+    multiplier = (multiplier * multiplier) % mod;
+    exponent >>= 1;
+  }
+
+  return product;
+}
+
+int main() {
+  using namespace std::string_view_literals;
+
+  std::string S{"hello"};
+  std::string_view s{S};
+  S.~basic_string();
+
+  // double ub - free + string view dereferencing destroyed object
+  // std::cout << s << '\n' ;
+
+  std::cout << -5 / 2 << '\n';
+
+  using namespace std;
+  long double ld = pow((long double)10, 18);  // computed in floating point
+  long long ll = (long long)ld;               // cast back to integer
+
+  cout << fixed << setprecision(0);
+  cout << "pow(10,18) as long double: " << ld << "\n";
+  cout << "cast to long long:         " << ll << "\n";
+  cout << "Should be exactly:         " << 1000000000000000000LL << "\n";
+
+  std::cout << binexp(2, 5, 5);
+
+  return 0;
+}