03 august 2004 nlp-ai java lecture no. 4 operators & decision constructs satish dethe
TRANSCRIPT
03 August 2004
NLP-AIJava Lecture No. 4
Operators & Decision Constructs
Satish Dethe
03 August 2004 [email protected]
• Increment Operator
• Decrement Operator
• Boolean Data Type
• Relational Operators
• Equality Operators
• Conditional Operators
• Selectional Constructs
Contents
03 August 2004 [email protected]
• i + + first use the value of i and then increment it by 1.
‘i + +’ equivalent to ‘i = (i)+1’. // postfix increment
• + + i first increment the value of i by 1 and then use it.
‘+ + i’ equivalent to ‘i = (i+1)’. // prefix increment
int i=2;
•System.out.print(“ i = ”+ i++);//print 2, then i becomes 3
•System.out.print(“ i = ”+ ++i);//add 1 to i, then print 4•Refer to incre.java
Increment Operators
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Decrement Operators
• i - - first use the i ’s value and then decrement it by one i - - equivalent to (i)-1. // postfix decrement• - - i first decrement i ’s value by one and then use it. - - i equivalent to (i-1). // prefix decrement
int i=5;System.out.print(“i = ” + i--);//print 5, then i becomes 4System.out.print(“i = ” + --i);//subtract 1 from i, then print 3Refer to decre.java
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This data type can store only two values; true and false. Declaring a boolean variable is the same as declaring any other primitive data type like int, float, char.
boolean response = false; //Validboolean answer = true; //Validboolean answer = 9943; //Invalid, boolean response = “false”; // Invalid,
This is return type for relational & conditional operators.
Refer to bool_op.java
Boolean Data Type
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Relational Operators
a < b a less than b. (true/false)
a <= b a less than or equal b. (true/false)
a > b a greater than b. (true/false)
a >= b a greater than or equal to b. (true/false)
These operations always return a boolean value.
System.out.println(“23 is less than 65 ” +23<65); // true
System.out.println(“5 is greater than or equal to 25.00?” + 5>=25.00); // false
Refer to relate.java
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a = = b a equal to b. (true/false)
a ! = b a not equal to b. (true/false)
boolean equal = 12 = = 150; // false
boolean again_equal = ‘r’= = ‘r’); // true
boolean not_equal = 53!=90); // true
Refer: equa.java
Equality Operators
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•A conditional operator is used to handle only two boolean expressions.
Boolean expression always returns ‘true’ or ‘false’.
•Conditional AND ‘&&’
Return value is ‘true’ if both, x and y are true, else it is ‘false’.System.out.println(“x&&y ” + x&&y); // Refer cond_and.java
•Conditional OR ‘||’
return value is true if any one of x or y, is true else it is false.System.out.println(“x||y ” + x||y); // Refer cond_or.java
Conditional Operators
03 August 2004 [email protected] [email protected]
The ‘ if ’ construct
It is used to select a certain set of instructions. It is used to decide whether this set is to be carried out, based on the condition in the parenthesis. Its syntax is:
if (<boolean expression>){
//body starts
<statement(s)>
//body ends
}
The <boolean expression> is evaluated first. If its value is true, then the statement(s) are executed. And then the rest of the program. Refer if_cond.java, if_cond1.java
03 August 2004
The ‘if else’ construct
It is used to provide an alternative when the expression in if is false. Its syntax is:
if(<boolean expression>){<statement(s)>
}else{
<statement(s)>}The if construct is the same. But when the expression inside if
is false then else part is executed.Refer ifelse_cond.java
03 August 2004
Assignments
int a_number=1; // (range: 1 to 5 including both)
Print the value of a_number in word. For example, it should print “Four” if a_number contains 4.
1. Use equality ‘= =’ operator.
2. Do not use equality ‘= =’ operator.
