CSC 201: Computer Programming I
B. S. Afolabi
1
Introduction
3 unit course
 2 hours of lecture/week




Thursdays 4.00pm – 6.00pm
Mondays 4.00pm – 6.00pm
3 hours of practical/week


To be determined next week
Course Lecturers:
Dr. A. O. Ajayi
Dr. F. O. Asaiah
Mrs. H. O. Odukoya
Dr. B. S. Afolabi
(Coordinator)
Dr. P. A. Idowu
Dr. A. R. Iyanda
Mr. I. P. Gambo
Mr. Okegbile
Miss Lawal
2
Textbooks
 No textbook is required
 For programming beginners:
Java Software Solutions: Foundations of Program Design, John Lewis and William
Loftus, Publisher: Addison Wesley, 2002
 For experienced programmers:
— Learning the JavaTM Language at http://docs.oracle.com/javase/tutorial/ /
— Thinking in Java, Bruce Eckel, Prentice Hall
Software is required

Download Java onto your home machine



http://www.oracle.com/technetwork/java/javase/downloads
/index.html
Follow the instructions to install it
Then, follow the instructions to install Eclipse

https://eclipse.org/downloads/
Functional versus imperative languages



Functional languages are ideal for expressing the functional (the
problem to be solved) component of any problem however...
at least 50% of all programs deal with input/output rather than a
problem and functional languages aren’t very good at input/output.
Think of the programs you use now:
editor
mail
language translator()
web browser

Functional programming should have taught you to appreciate concise
elegant programs.
The Computer
Central
Processing
Unit (CPU)
Memory
Input /
Output
Devices
CPU Instructions
z=x+y
Read location x
Read location y
AddWrite to location z
Programming Languages
Easier to understand than CPU instructions
 Needs to be translated for the CPU to
understand it

JAVA
 “Most
popular” language
 Runs on a “virtual machine”
(JVM)
 More complex than some (eg.
Python)
 Simpler than others (eg. C++)
Compiling Java
Source
Code
(.javac
)
javac
Byte
Code
(.class)
java
First Program
class Hello {
public static void main(String[]
arguments){
//Program execution begins here
System.out.println("Hello world.");
}
}
Program Structure
class CLASSNAME
public static void main(String[]
arguments){
STATEMENTS
}
}
Output
System.out.println(some String) outputs to
the console
Example:
System.out.println(“output”);
Second Program
class Hello2 {
public static void main(String[]
arguments){
//Program execution begins here
System.out.println("Hello world.");
//Print once
System.out.println(“Line number 2.");
// Again
}
}
Types
Kinds of values that can be stored and
manipulated.
boolean: Truth value (true or false).
int: Integer (0, 1, -47).
double: Real number (3.14, 1.0, -2.1).
String: Text (“hello”, “example”).
Variables
Named location that stores a
value of one particular type.
Form: TYPE NAME;
Example:
String foo;
Assignment
Use “=“ to give variables a value.
Example:
String foo;
foo = “IAP 6.092”;
Assignment
Can be combined with a
variable declaration.
Example:
double badPi = 3.14;
boolean isJanuary = true;
class Hello3 {
public static void main(String[]
arguments){String foo = "IAP 6.092";
System.out.println(foo);foo =
"Something else";
System.out.println(foo);
}
}
Operators
Symbols that perform simple
computations
Assignment: =
Addition: +
Subtraction: Multiplication: *
Division: /
Order of Operations
Follows standard math rules:
Parentheses
Multiplication and division
Addition and subtraction
class DoMath {
public static void main(String[]
Arguments){
double score = 1.0 + 2.0 * 3.0;
System.out.println(score);
score = score / 2.0;
System.out.println(score);
}
}
class DoMath {
public static void main(String[]
Arguments){
double score = 1.0 + 2.0 * 3.0;
System.out.println(score);
double copy = score;
copy =copy/ 2.0;
System.out.println(copy);
System.out.println(score);
}
}
String Concatenation (+)
String text = "hello" + " world";
text = text + " number " + 5;
// text = "hello world number 5"
Examples 1
class Comment {
// This is a one-line comment; it extends to the end of the line
/* This is a delimited comment, extending over several lines
*/
int /* A delimited comment, extending over part of a line */ x = 117;
}
25
Examples 2
class Layout { // Class declaration
int a;
Layout(int a)
{ this.a = a; } // One-line constructor body
int sum(int b) { // Multi-line method body
if (a > 0) // If statement
return a + b; // Single statement
else if (a < 0) { // Nested if-else, block statement
int res = -a + b;
return res * 117;
} else { // a == 0 // Terminal else, block statement
int sum = 0;
for (int i=0; i<10; i++) // For loop
sum += (b - i) * (b - i);
return sum;
}
}
26
…Examples 2
static boolean checkdate(int mth, int day) {
int length;
switch (mth) { // Switch statement
case 2: // Single case
length = 28; break;
case 4: case 6: case 9: case 11: // Multiple case
length = 30; break;
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
length = 31; break;
default:
return false;
}
return (day >= 1) && (day <= length);
}
}
27
Example 4
class Scope {
... //
void m1(int x) { // declaration of parameter x (#1)
... // x #1 in scope
} //
... //
void m2(int v2) { //
... // x #5 in scope
} //
... //
void m3(int v3) { //
... // x #5 in scope
int x; // declaration of variable x (#2)
... // x #2 in scope
} //
... //
28
…Example 4
void m4(int v4) { //
... // x #5 in scope
{ //
int x; // declaration of variable x (#3)
... // x #3 in scope
} //
... // x #5 in scope
{ //
int x; // declaration of variable x (#4)
... // x #4 in scope
} //
... // x #5 in scope
} //
... //
int x; // declaration of field x (#5)
... // x #5 in scope
}
29
30