1. UNIT 2. Introduction to Computer Programming

2. UNIT 2. Introduction to Computer Programming
Algorithm & Flowcharting
COM E 211: Basic Computer Programming

3. Algorithm & Flowcharting
A list of instruction that carries out a process step by step
Flowchart
A diagram representing the logical sequence in which a combination of steps or operations is to be performed
Is usually a visual representation of an algorithm
Types of Flowchart:
Program Flowchart
Describes graphically in detail the logical operations & steps within a program
System Flowchart
A graphic representation of procedures involved in converting data or input to data in output form.
COM E 211: Basic Computer Programming

4. COM E 211: Basic Computer Programming
Advantages of Flowchart
Language independent
Enforces user to give attention to significant matters
Provides an alternative to the usual narrative description
Easier to understand
Limitations
Do not represent a programming language
Can’t be viewed as a natural means of communication
Certain details often require a long sequence of interconnected symbols
Does not convey why a given set of operations is made
Do not highlight the important detail since each step receives as much attention in a flowchart as any other.
COM E 211: Basic Computer Programming

5. COM E 211: Basic Computer Programming
Flowcharting Symbols
Parallelogram Input / Output
Rectangle Processing
Diamond Decision
Small Circle On-page Connector
Pentagon Off-page Connector
Arrow Heads Flow Direction Indicators
Horizontal / Vertical Lines --- Flow Lines
Oval Terminal
COM E 211: Basic Computer Programming

6. Examples for Sequential
The radius of a circle is equal to 1 unit. Make an algorithm and draw a flowchart to compute the corresponding area of the circle and print out the value of the radius and the area.
Given three(3) numbers A,B and C. Make an algorithm and draw a flowchart to compute and print out the sum, the average and the product of these values.
COM E 211: Basic Computer Programming

7. Examples for Branching
The ABC manufacturing company plans to give a year-end bonus to each of its employees. Make an algorithm and draw a flowchart which will compute the bonus of an employee. Consider the following criteria: If the employee’s monthly salary is less than 1,000, the bonus is 50% of the salary. If the salary is grater than 1,000, the bonus is 1,000. Print out the name and corresponding bonus of the employee.
Given two (2) numbers, x and y. Make an algorithm and draw a flowchart to determine the difference between x and y. If x-y is negative, compute R=x+y; if x-y is zero, compute R=2x+2y; and if x-y is positive, compute R=x*y. Ptint out the values, x, y and R.
COM E 211: Basic Computer Programming

8. COM E 211: Basic Computer Programming
Loops and Counter
Looping
Used when it is desired to make the same calculation of more than one set of data. It consists of repeating a program, or a section of program and substituting new data for each repetition.
Counter
Is a setup in a program loop to keep track of a number of times the program segment is repeated. The program can then be terminated after the completion of a predetermined number of passes.
Steps in Loop Control
Initialization
The value of counter is initially set equal to zero or one.
Test for limit condition
Before the logic flow gets out of a loop, a loop terminating condition must first be satisfied.
Incrementation
Often each loop is executed, 1 is added to the counter. Thus counter reflects the number of times the operation has been performed.
COM E 211: Basic Computer Programming

9. COM E 211: Basic Computer Programming
Examples for Looping
The initial value of the radius of a circle is equal to one unit and each succeeding radius is one unit greater than the values before it. Make an algorithm and draw a flowchart to compute the area of the circle starting with R=1.0 up to R=5.0, then print out each radius and corresponding area of the circle.
Given a set of five (5) numbers that includes both positive and negative data values. Make an algorithm and draw a flowchart to read in these values one at a time and count the number of positive values (including zero value) and the number of negative values found in the set. After the required values are determined, print out these counted values.
COM E 211: Basic Computer Programming