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--- programming:cplusplus:start [2019/10/19 20:14]
dwheele [Difference between Dot and Arrow]
+++ programming:cplusplus:start [2022/02/28 18:43] (current)
dwheele [Reference]
@@ Line 2: / Line 2: @@
 Helpful tutorials on YouTube are by TheChernoProject https://www.youtube.com/channel/UCQ-W1KE9EYfdxhL6S4twUNw
+(Too much of a beginner) Trying course from https://www.youtube.com/watch?v=vLnPwxZdW4Y
+===== include =====
+Includes library of code, either from local (name is in double-quotes) or in the language-provided libraries (name is in angle-brackets).
+<code c++>
+#include <iostream>
+</code>
+Use angle brackets for built-in libraries.
+===== using namespace =====
+<code c++>
+using namespace std;
+</code>
+Places this code into the std namespace. That way, we can use ''cout'' instead of ''std::cout''. However, I don't use this namespace because TheCherno says not to, instead, always give explicit namespace value.
+===== Linker =====
+The C++ compiler creates and Object file, but separately. The Linker puts them together.
+===== Pointers =====
+https://www.youtube.com/watch?v=DTxHyVn0ODg&list=PLlrATfBNZ98dudnM48yfGUldqGD0S4FFb&index=16
+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>
 ===== Memory =====
@@ Line 50: / Line 162: @@
 To access members of a structure, use the dot operator. To access members of a structure through a pointer, use the arrow operator. [[https://www.tutorialspoint.com/cplusplus/cpp_member_operators.htm|Details]]
+====== Troubleshooting while Building ======
+Sometimes the *.h.gch will get corrupted or contain outdated information, so deleting that file and compiling it again should fix it. [[https://stackoverflow.com/questions/1241399/what-is-a-h-gch-file|Details]]

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