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Hello World 2 What does all that mean?.

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Presentation on theme: "Hello World 2 What does all that mean?."— Presentation transcript:

1 Hello World 2 What does all that mean?

2 The Evolution of Programming Languages
Early computers programmed in machine language To calculate wages = rate * hours in machine language: //Load //Multiply //Store

3 The Evolution of Programming Languages (cont’d.)
Assembly language instructions are mnemonic Assembler: translates a program written in assembly language into machine language

4 The Evolution of Programming Languages (cont’d.)
High-level languages Express algorithms at a more abstract level: int wages = rate * hours; Ex: Basic, FORTRAN, COBOL, Pascal, C, C++, C#, and Java Current popularities

5 The Evolution of Programming Languages (cont’d.)
Compiler: translates a program written in a high-level language into machine language

6 Processing a C++ Program (cont’d.)
To execute a C++ program: Create a text source program in C++ Preprocessor directives begin with # and are processed by the preprocessor Compiler: Checks that the program obeys the language rules Translates into machine language (object program)

7 Processing a C++ Program (cont’d.)
To execute a C++ program (cont'd.): Linker: Combines object program with other programs provided by the SDK to create executable code Library: contains prewritten code you can use

8 How the code works: # : preprocessor directive
Instructions to do before compiling Bring the code from the library iostream into this file

9 How the code works: Use all the names that are in the "standard" grouping in my program Alternative:

10 How the code works: ; statement terminator Ends a "sentence of code"

11 How the code works: int main() The starting point of our program
Program instructions go inside { }

12 How the code works: Comment : computer ignores
// : rest of line is comment /* : everything is comment until */ /** : special comment – machine readable

13 Documentation Every file should have comment like this at top:

14 How the code works: cout : console output

15 How the code works: cout : console output << "send to output"

16 How the code works: cout : console output << "send to output"
"Hello" : a string – piece of text

17 How the code works: cout : console output << "send to output"
"Hello" : a string – piece of text endl : symbol representing "end of line"

18 How the code works: return 0 Program ran successfully
Anything BUT 0 indicates error

19 Working with numbers We can output numbers to console:
Can do math using + - / * Division may give interesting results…

20 Everything Counts Indentation & Style matter (to humans)
Spelling & Capitalization matter (to humans & computers)


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