Cpp basic 2 demo

M-cpp/code/Makefile

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+CC=g++
+CXX=g++
+CXXFLAGS=-g -Wall -std=c++11
+LDFLAGS= -g
+
+TARGS=cpp-basic-2
+default: $(TARGS)
+
+cpp-basic-2:
+cpp-basic-2.o:
+
+clean:
+	rm -rf $(TARGS) *.o a.out
+
+.PHONY: default clean

M-cpp/code/README.md

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+C++ Basic 2 Demo
+================
+
+This is a simple code demo that will show you when constructors and destructors
+are called.
+
+Constructors are called when objects are declared and initialized, while
+destructors are called at the end of the **block** an object is declared.
+This is usually at the end of the curly brace that closes that block,
+but this example demonstrates that it is also the case for the ends of one-liner
+conditional and looping statements.
+
+
+Building and running
+--------------------
+
+To build, type `make`.
+To run, just run `./cpp-basic-2`.
+
+Feel free to modify the code as you wish to try out your own examples.

M-cpp/code/cpp-basic-2.cpp

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+#include <cstdio>
+#include <iostream>
+
+using namespace std;
+
+class Echoer {
+public:
+    int id;
+    Echoer(int eid) {
+        id = eid;
+        cout << "constructor: " << id << endl;
+    }
+
+    ~Echoer() {
+        cout << "destructor: " << id << endl;
+    }
+
+    void echo() {
+        cout << "echoer: " << id << endl;
+    }
+};
+
+int main(void)
+{
+    Echoer e0 = Echoer(0); // created in main() block, not destroyed until end
+
+    {   // new block
+        Echoer e1 = Echoer(1);
+    }   // end block, e1 destructor called
+
+    if (1)
+        Echoer e2 = Echoer(2);
+        // there is an implicit block at the end of one-liner conditionals
+        // even if there is no end curly brace
+
+    int i;
+    for (i = 3; i < 6; i++)
+        Echoer ei = Echoer(i);
+        // same with one-liner looping statements
+        // each ei will be destroyed before the next iteration
+
+    return 0;
+}   // end of main() block, e0 destroyed here