Introduction to Computer Programming - part 5

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INTRODUCTION TO PROGRAMMING

I am collating my study notes as part of my education into Computer Programming. In an attempt to increase and improve my own learning, and to help others also (learn by teaching) I will be sharing my notes, as neatly presented as possible, for others to follow along with if they so wish. This is Lesson 5's notes.

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EARLIER LESSONS

Lesson 1 Notes
Lesson 2 Notes
Lesson 3 Notes
Lesson 4 Notes

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INTRODUCTION TO COMPUTER PROGRAMMING – STUDY NOTES

LESSON 5

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CONTROL FLOW

Control Flow = creating an order in which statements will be executed in a program.

We touched briefly on Control Flow in lesson 4 where we discussed Conditional Statements. In this lesson we are looking at Loops.

Loops = a loop has a condition, and so long as that condition is true, the code will continue to run. When it become false then the code will end.

LINK: Control Flow

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While Loop

initialise
while (true){
    do this
    increment/decrement
}
more code

The above example prints out a line (I will be good in class) 50 times. The code checks that X is less than or equal to 50, and so long as that is true then the statement gets printed. When the code becomes false (x > 50) then the code will exit the loop.

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Do-while Loop

initialise
do {
    do this
    increment/decrement
}
while (true)
more code

The difference between the Do-While Loop and the While Loop is that the Do-While Loop will be executed at least once, whereas the While-Loop contains the possibility that the code wont get run at all.

The example is similar code to the above, but has been written as a Do-While Loop, and had X changed to 100. This makes the While statement false. This example is to illustrate that the code still prints out once (see line at bottom of screenshot that says '100: I will be good in class'.)

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For Loop

for (initialisation; condition; increment/decrement){
    statement;
}
more code

The For Loop puts everything into the brackets and determines if it's true before running the statement.

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Jump Statements

Break = used to immediately jump out of a loop block.

The above example runs the loop, and then forces the loop to stop when X==10. At that point it is now outside the loop code.

Continue = skips the rest of a loop and jumps back to the top of the loop.

In the above example the If Statement is true if the number is odd. (X%2 == 1) is true if the number is odd, and this causes the Continue Statement to run, causing the odd number not to print (instead the loop continues back to the top), and the loop starts again from the last (non-printed) number. In other words, this loop will print the even numbers, and skip the odd numbers.

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RECAP OF EARLIER LESSONS

In Lesson 1 we briefly looked at:

• What is a programming language?
• Language Types – especially HIGH Level and LOW Level.
• Compiled vs Interpreted Languages
• Data Types: Strongly Typed vs Weakly Typed Languages.
• Data Types: The most common data types (characters, integers, floating-point, fixed-point, boolean, reference).

In Lesson 2 we looked briefly looked at:

• Variables
• Constants

These both flow on from Data Types and work with these.

In Lesson 3 we looked briefly at:

• Operators

Used to allow operations (such as multiplication) to be performed on variables or constants.

In Lesson 4 we looked briefly at:

• Conditional Statements

If, If-Else, If-Then Statements, which are used to control the flow of a program.

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FURTHER DATA

cpp.sh - C++ shell website
Scratchpad - Shift + F4 on Firefox - Javascript shell
Dev C++ - A free, portable, fast and simple C/C++ IDE
Code::Blocks - A free C, C++ and Fortran IDE
Ideone - an online compiler and debugging tool which allows youto compile source code and execute it online in more than 60 programming languages.

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My Posts

Introduction From a Newbie Programmer and Intro - part 2
Introduction to Computer Programming - part 1 (Lesson 1)
Introduction to Computer Programming - part 2 (Lesson 2)
Introduction to Computer Programming - part 3 (Lesson 3)
Introduction to Computer Programming - part 4 (Lesson 4)

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