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C++ Programming BasicsChapter 1 Lecture

CSIS 10A

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Agenda

Hardware Basics The IDE

My First Program

Its all G(r)eek to me

Variables and Declarations

Input and Output

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Anatomy of a Computer

Memory Output

ALU Control Input

MouseKeyboardScanner

Hard DiskFloppy Disk

MonitorPrinterSpeakers

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The CPU uses machine languageAssembly instructions to calculate the radius of a

circle:

LOAD radiusLOAD piMULTIPLYLOAD twoMULTIPLYSTORE circle

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Compilers to the Rescue !

High level languages like C++ allows writing code that is easier to understand and universally works on any CPU.

circle=2.0*radius*pi;

The compiler is what translates instructions from C++ into Machine language.

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Agenda

Hardware Basics

The IDE My First Program

Its all G(r)eek to me

Variables and Declarations

Input and Output

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THE MECHANICS OF WRITING A PROGRAM

1. Editing -- Writing a program 2. Compiling -- Translating from C++ into machine language 3. Linking -- Combining your program with other libraries4. Running – Letting the computer execute a program5. Debugging – Running step by step through a program

searching for mistakes

The Integrated Development Environment (IDE) combines 1-5.

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Agenda

Hardware Basics

The IDE

My First Program

Its all G(r)eek to me

Variables and Declarations

Input and Output

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Hello World !

Lets start off the traditional way

Program that prints out “Hello World” on your output console (your screen)

Lets start off on our journey…..

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Steps

1. Create new source file

2. Write the code

3. Create a workspace (only in MSVC++)

4. Compile

5. Link

6. Execute

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Agenda

Hardware Basics

The IDE

My First Program

Its all G(r)eek to me

Variables and Declarations

Input and Output

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It’s all G(r)eek to me

… actually, its C++

Lets dissect and analyze a simple program

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20,000 ft. above sea level

#include <iostream>using namespace std;

int main(){// This is my first program cout << "Hello World" << endl; system("pause"); return 0;}

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20,000 leagues under the sea

#include <iostream>

Actually includes some information into your code

Contains some definitions that are needed for your code

More of this later on in the course

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22,000 leagues under the sea

using namespace std;

This line refers to a set of standard object name definitions

For now, this is “boilerplate”—stick it in cause it makes everything work!!

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… deeper….

int main()

• This is the piece of code (function) that is operated on first when a program is executed

• What’s a function ???

• …. all that’s coming soon …

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… even deeper….

//This is my first program

• This is a comment you write to yourself

• Useful when writing large programs

• Starts with a //

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… and deeper…..

Output operator

cout << “Hi”<<endl;

cout is the console monitor (your display)

<< is the output operator. Use to chain together your output message.

“Hi”is a string literal

endl means end-line (like enter key)

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… getting sleepy?…..

For the Bloodshed environment…Hold the display open so you can read it (pressing a key will continue) system("pause");

Finish up this program, return a 0 to operating system (everything ended OK)

return 0;

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… and even deeper ….

{} delineates the code block

Each line ends with a ;

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Other types of cout statement

cout<< “ my age is” <<endl << 39<<endl;

cout<< “ my age is 39”;

cout<< “ what’s your’s”;

Escape with \

Output a “ cout<<“ \” ” <<endl;

Output a endl cout<<“\n”;

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Tom’s All Purpose Program Shell#include <iostream>using namespace std;

int main(){// Your code here ...

system("pause"); return 0;}

Future slides may neglect some of the above components for clarity

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You Do ItModify your hello world program to print your name, address and phone number (COULD BE FAKE!) on three lines:

Tom Rebold1600 Pennsylvania Ave123-456-7890

Experiment with line breaks

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Lets get moving…..

We’ll learn as we proceed

You’ll be saying “Aha!” or “Oho!” when you hear these terms again

Let’s play around a bit more

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What more ?

Variables and Declarations

Getting User Input

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Variables and Declarations

Variables represent storage locations in the computer’s memory

variable = expression

Assignment is from right to leftn = 5;

Would give n the value 5

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Using int Variables

int main()

{

int m,n;

m = 44;

cout << “m = “ << m;

n = m + 33;

cout << “ and n = “ << n << endl;

}

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Clearing the haze

int m;

m

int

m = 44.0; 44

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Clearing the haze

int m = 44, n;

44 + 33 = 77

intn

m

int

44

77

n = m + 33;

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Want more ?

Variables and Declarations

Getting User Input

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User Input with cin

How shall I feed in data ?

Remember cout ?

Meet cin

cin >> m;

Will put the value entered through the console (keyboard) into m

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User Input with cin

int main(){cout << "Enter the value of m:";cin >> m;cout << "m = " << m << endl;

}

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User Input with cin

int main(){cout << “Enter the value of m:”;cin >> m;cout << “m = “ << m << endl;

}

HEY THERE’S SOMETHING WRONG

HERE !!!

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User Input with cinint main(){int m;cout << "Enter the value of m:";cin >> m;cout << "m = " << m << endl;

}

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Your turn ()

1. from hello.cpp File>SaveAs age.cpp

2. Delete all the cout statements. Add lines to:

a) Declare a variable called age

b) Display a message asking for data (such as “tell me your age”)c) read the data into age d) display the variable age with a descriptive message. (refer to slide 34)

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That’s a wrap !

What we learned so far:How to write a basic C++ program

The structure of a program

Displaying to the console (cout)

Variables

Getting user input via the console (cin)