C++ Programming Basics Chapter 1 Lecture CSIS 10A
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Transcript of C++ Programming Basics Chapter 1 Lecture CSIS 10A
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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)