Intermediate C++ Game Programming Tutorial 1

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We've been using ints and floats and bools this whole time, but have you ever wondered about a day in the life of a variable? In this video, we find that shit out, and so much more. We also learn about the cousins of int and float, adding to our arsenal of basic data types we can use in our programs. What's the endgame you ask? This stuff is gonna help us understand pointers and strings, and it's just interesting shit.

Topics Covered

  • The concept of memory (RAM)
  • Binary and hexadecimal number systems
  • char, short, long long, double
  • unsigned integral types
  • The ranges and sizes of basic data types
  • Layout of variables in memory
  • Correspondence between C++ code and CPU operations

Video Timestamp Index

Tutorial 1

Bonus Video: Red Pill [The Stack]

The description of how variables are organized in memory in Tutorial 1 is a simplified model that will help us understand memory and pointers; it is not 100% accurate.

Chili had originally planned to teach the full details of how variables are allocated, explaining things like storage classes (stack, heap, static), the details of stack management and function stack frames, and exploration of the memory and machine instructions using the debugger. But then he realized that this amount of detail and complexity might be too much of a mind fuck for too many people, so he cut that content from Tutorial 1.

Since the video is already recorded, it will be released as optional content for people who are interested in the nitty-gritty details, but the keyword here is optional; you are not required to know this content to continue on with the tutorials and it will not be referred to in the mainline tutorial series. It is, however, very interesting shit.

Video link: Red Pill - The Stack

Homework

This lesson's homework is to answer the following questions. When you think you have the answer, click "expand" to reveal the correct answer.

1. In Microsoft Visual C++, what is the size in bytes of the following data types: int, char, double, unsigned int, short, bool

int: 4
char: 1
double: 8
unsigned int: 4
short: 2
bool: 1


2. Make the following conversions: 01000111b -> dec, 11001111b -> hex, 10h -> dec, 7Ah -> bin, 193d -> bin

01000111b -> dec: 71
11001111b -> hex: CF
10h -> dec: 16
7Ah -> bin: 01111010
193d -> bin: 11000001


3. What is the size of this class in bytes with default compiler settings in Microsoft Visual C++, and how many of those bytes are padding:

class Foo
{
public:
	int a;
	char b[3];
	short c;
	int d;
};

16 bytes (3 bytes padding)


4. Why is hexadecimal commonly used to represent values in programming?

It's easy to convert between hexadecimal and binary representations, and hexadecimal takes far fewer digits to represent the same number.


5. When accessing variables in memory, often times many addition/multiplication operations must be performed to index into arrays or access elements of classes/structures. What is one way the compiler can optimize this for runtime performance?

If the indices and offsets are values that are known at compile time, the addresses will be pre-computed at compile time and not at runtime.


See also