add 013_VarScopes_and_Namespace.cpp

Author: priteshgohil

013_VarScopes_and_Namespace.cpp

@@ -0,0 +1,74 @@
+#include<iostream>
+using namespace std;
+
+// Memory Segments
+// https://ozh.github.io/ascii-tables/
+
+// +--------+------------------------------------------+
+// | FFFFh  |                                          |
+// |        |                                          |
+// | Static | Local variables                          |
+// |        | Parsed arguments to function             |
+// |        | Recursive function call                  |
+// +--------+------------------------------------------+
+// |        |                                          |
+// | Heap   |                                          |
+// |        | Dynamically allocated variables/memory   |
+// +--------+------------------------------------------+
+// |        | Initialized variable Local/Global        |
+// |        |                                          |
+// |        |------------------------------------------+
+// | Data   |                                          |
+// |        | .bss (uninitialized variables)           |
+// |        | global, static, extern variables         |
+// |        | Note: not occupying but only in .obj file|
+// +--------+------------------------------------------+
+// |        |                                          |
+// |        |                                          |
+// | Text   | compiled program                         |
+// |        | Machine code                             |
+// | 0000h  | Crt.o (startup routine                   |
+// +--------+------------------------------------------+
+
+
+
+namespace MyNamesapce {
+  int a, b;
+  long int lnNum = 10;
+  int sum(int num1, int num2){
+    return num1+num2;
+  }
+}
+
+// variable scopes
+int x = 55;         //global scope
+void increment (int num){
+  cout << "Increment " << num << " by 1 = " << ++num << endl;
+  // increment(++num);         // stack overflow, cz function pointers and local
+                            // variables are stored in stack
+}
+
+int main(int argc, char const *argv[]) {
+  cout << "using only \"cout\" instead of \"std::cout\"" << '\n';
+  cout << "MyNamesapce::lnNum = " << MyNamesapce::lnNum << endl;
+  // access namespace items
+  using namespace MyNamesapce;
+  cout << "lnNum = " << MyNamesapce::lnNum << endl; //scope resolution operator not req.
+  cout << "sum of 5 + 7 = " << sum(5,7)<< '\n';
+  // namespace aliasing
+  namespace NewName = MyNamesapce;
+  cout << "sum of 5 + 7 = " << NewName::sum(5,7)<< '\n';
+
+  // Scope of variables
+  cout << "x = " << x << '\n';
+  int x = 5;                        // local scope
+  {
+    int x = 10;                     // inner scope
+    cout << "x = " << x << '\n';
+  }
+  cout << "x = " << x << '\n';
+
+  // stackoverflow error
+  increment(1);
+  return 0;
+}