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--- programming:cplusplus:start [2022/02/28 18:16]
dwheele [Pointers, References]
+++ programming:cplusplus:start [2022/02/28 18:43] (current)
dwheele [Reference]
@@ Line 32: / Line 32: @@
 https://www.youtube.com/watch?v=DTxHyVn0ODg&list=PLlrATfBNZ98dudnM48yfGUldqGD0S4FFb&index=16
-A pointer is an integer which stores a memory address.
+A pointer is an integer which stores a memory address. Types have nothing to do with that.
+The value 0 is not a valid memory address. It means 0
+<code c++>
+int main()
+{
+   // void* ptr = 0; // or   void* ptr = nullptr;
+   int var = 8;
+   // Where are you in memory
+   int* ptr = &var; // Get the location of var, and put it into ptr as an integer pointer.
+   *ptr = 9; // int value pointed at by pointer "ptr"
+   std::cin.get();
+}
+</code>
+<code c++>
+int main()
+{
+   char* buffer = new char[8];// This uses heap
+   memset(buffer, 0, 8);
+   char** ptr = &buffer;// Pointer to a pointer
+   delete[] buffer;// delete afterward to be nice
+   std::cin.get()
+}
+</code>
 ===== Reference =====
+Pointers and references are about the same thing. How we write them is different. References are syntax sugar on top of a pointer.
+References reference an existing variable.
+<code c++>
+int main()
+{
+   int a =5;
+   int& ref = a;// the & is part of the int defintion
+   // We have created an alias. It is not really a variable.
+   // We can use ref as though it is "a"
+   ref = 2;
+   std::cout(ref);
+}
+// Works, but this is clumsy
+void Increment (int* value)
+{
+   (*value)++;// Value at the pointer "value"
+}
+int main()
+{
+   // We want to pass the memory address.
+   int a = 5;
+   Increment(&a);
+   LOG(a);
+}
+</code>
+<code c++>
+// Use a reference instead of a pointer
+void Increment(int& value)
+{
+   value++;
+}
+int main()
+{
+   int a = 5;
+   Increment(a);
+   LOG(a)
+}
+</code>

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