Study results from Stroustrup's PPP3 book.

PPP3/ex05.cpp

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+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <stdexcept>
+
+using namespace std;
+
+class ExpectFail {
+  public:
+    string message;
+
+    ExpectFail(string m) : message(m) {};
+};
+
+void expect(bool test, string msg) {
+  if(!test) {
+    throw ExpectFail("Expectation failed.");
+  }
+}
+
+int area(int length, int width) {
+  expect(length > 0 && width > 0, "Bad area given.");
+
+  return  length * width;
+}
+
+int main() {
+  vector<int> numbers;
+
+  try {
+    numbers.push_back(100);
+    numbers.push_back(-100);
+
+    cout << "Area " << area(numbers.at(1), 100) << "\n";
+
+    return 0;
+  } catch(out_of_range &e) {
+    cout << "Out of range ERROR: " << e.what() << "\n";
+    return 2;
+  } catch(...) {
+    cout << "Exception: something went wrong\n";
+    return 3;
+  }
+}