CSCI261C/E Lecture 2: C++ Fundamentals August 29, 2011 Programming - - PowerPoint PPT Presentation

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CSCI261C/E Lecture 2: C++ Fundamentals August 29, 2011 Programming - - PowerPoint PPT Presentation

Nov 24, 2023 198 likes •535 views

CSCI261C/E Lecture 2: C++ Fundamentals August 29, 2011 Programming is cool! Bjarne Stroustrup http://en.wikipedia.org/wiki/Bjarne_Stroustrup This is not what I mean by cool . Note the white jeans. (whatever) Atribution: Wired Magazine Huh?

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CSCI261C/E

Programming is cool!

Lecture 2: C++ Fundamentals August 29, 2011

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Bjarne Stroustrup

This is not what I mean by cool. Note the white jeans.

http://en.wikipedia.org/wiki/Bjarne_Stroustrup

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(whatever)

Atribution: Wired Magazine

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Huh? Wha? (review)

  • computer system = hardware + software
  • programming = describing algorithms to a

computer

  • abstraction = don’t worry about the details

(as long as it works)

  • we speak english, computers speak binary
  • programming languages bridge the gap
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Review

We declare constant “facts” using the const keyword.

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Review

  • We compiled and ran a program
  • But... “what happened?”

Attribution: MCA Records

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We “talked” to the machine by giving it commands. (a program*)

* Cool kids call this code. (Always singular unless you’re speaking lolcat.)

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Concept #0

We talk to the machine through programs (“code”). The machine understands and follows our commands. But, it has to “translate” our program into “computerese.” Why? We speak in English, computers speak in binary.

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Concept #0

“translate to computerese”

Compile, link and execute.

(“run” not “kill”)

“compile to machine code (binary)”

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Big Picture

source code compiler

  • bject file

source code compiler

  • bject file

linker libs executable

main.cpp testApp.cpp OpenFrameworks stdio string main.o testApp.o helloWorld.exe

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Implement

  • You write a program in a “programming language”
  • The language is easy for the machine to read
  • ... and easy enough for humans to read & write
  • (some languages are more “human” than others)

For example, Ruby!

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Compilation

  • Visual Studio contains a compiler
  • (shy and likes to hide behind )
  • Reads the C++ source file
  • Translates it into machine code
  • Produces an “object file”
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What’s an Object File?

  • Contains machine instructions, data
  • Typically never directly executed
  • Destined to be combined with other object

files into a “program” or “executable”

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What’s an Object File, Really?

Structured encoding of one .cpp file. Six segments.

  • bject file

header text segment data segment

relocation information

symbol table debugging info

main.cpp’s instructions main.cpp’s data

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Linking

  • Your program relies on other source files

and libraries (if not, it’s probably boring)

  • The linker combines multiple object files
  • Produces an executable program
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Execution

  • Executable programs first reside on disk
  • To “execute” a program means to:
  • Load the executable file into memory
  • Tell the computer where the first

instruction is

  • Go! Go!
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Your Program in Memory

Stack Dynamic Data Static Data Text (Instructions)

Your final program’s instructions Your final program’s data

}

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What to Remember

  • We write instructions and declare data in .cpp files
  • .cpp files get compiled to object files
  • object files get linked and become an executable

program

  • execution means your program is loaded into

memory and the computer is carrying out your instructions

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C++ Program Structure

preprocessing directives int main() { variable declarations; statements; return 0; }

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Preprocessing Directives

Things (aka ‘libraries’) your program will need to use. eg, math functions, input/output, graphics #include <iostream> #include <cmath>

“Hey computer, my program uses functions in the iostream library and the math library.”

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main()

Is special -- all programs start with main. What does your program do? Whatever is in the code block following main().

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Code Blocks

{ the stuff in between braces } The guts of your algorithm

int main() {

/* computer, what should I do with my life? */ return 0;

}

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Concept #1

We need to declare facts about the world to the machine. Facts that can change over time? Variables.

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Variable Declarations

  • A computer is dumb
  • All variables have a data type
  • Why?

You need to tell the computer ahead of time about the memory you will need

  • Why? Because variables need

memory

  • Why? To store values
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Data Types of Variables

  • int
  • double
  • char
  • boolean
  • string (technically, not a standard type)
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...to be continued

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Concept #7

We need to communicate with the machine while our program is running. We want the machine to generate a response. “Put stuff in, get stuff out.”

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Input / Output

aka I/O

#include<iostream>

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cout

“the screen” aka “character output” or “standard output”

cout << “does he/she like me?”; cout << “does he/she like me?” << “or looove me?”;

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cin

“the input prompt on a screen” aka “character input” or “standard input”

cin >> answer;

“Computer, take what the user types when they hit [enter] and assign it to the variable following the >> symbol”

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Homework

  • Read Chapter 2
  • Complete 02_sphereVolume