If-Else¶

Example¶

Let's start with real world example of ordering coffee from a cafe :-

The customer might ask the receptionist If you have coffee then provide coffee.

Or If you have coffee then provide coffee, else provide tea

In programming we have to tackle real world situations.
How can we tackle the situation described above in the example using programming ?
If we pay attention to questions asked in the example we find the following keywords If & Else.
We can code the above situations using if else conditions.

If-Else Syntax¶

if(is coffee available ? ){
 //   serve coffee
}
else{
 // serve tea
}

Is coffee available ? is the Condition.
The condition is statement which can have only true/false as answers or we say it's of boolean type

Question 1¶

Question¶

Given an integer age as input, print whether the person is eligible to vote or not ?

A person is eleigible if the person's age >= 18

Testcase 1¶

Input :
20

Solution 1¶

Output : Eligible

Testcase 2¶

Input :
14

Solution 2¶

Output : Not Eligible

Approach¶

Using conditional statements we check:
If age is >= 18 print Eligible.
Else print Not Eligible

Pseudeocode¶

public static void main() {

    if (age >= 18) {
        System.out.print("Eligible");
    } else {
        System.out.print("Not Eligible");
    }
}

Question 2¶

Question¶

Given two integers A and B as input, print the larger

A will not be equal to B

Testcase 1¶

Input :
A = 4, B = 6

Solution 1¶

Output : 6 is bigger

Testcase 2¶

Input :
A = 9, B = 6

Solution 2¶

Output : 9 is bigger

Approach¶

Using conditional statements we check:
- If A > B print A is bigger.
- Else print B is bigger.

Pseudeocode¶

public static void main() {

    scn = new Scanner(System.in);

    int A = scn.nextInt();
    int B = scn.nextInt();

    if (A > B) {
        System.out.print(A + "is bigger");
    } else {
        System.out.print(B + "is bigger");
    }
}

¶

Question 2 part 2¶

Question¶

Given two integers A and B as input, print the large

Testcase 1¶

Input :
A = 4, B = 6

Solution 1¶

Output : 6 is bigger

Testcase 2¶

Input :
A = 9, B = 6

Solution 2¶

Output : 9 is bigger

Testcase 2¶

Input :
A = 6, B = 6

Solution 2¶

Output : Both are equal

Approach¶

Using conditional statements we check:
- If A > B print A is bigger.
- Else if A < B print B is bigger.
- Else print Both are equal.

Pseudeocode¶

public static void main() {

    scn = new Scanner(System.in);

    int A = scn.nextInt();
    int B = scn.nextInt();

    if (A > B) {
        System.out.print(A + "is bigger");
    } else if (B > A) {
        System.out.print(B + "is bigger");
    } else {
        System.out.print("Both are equal");
    }
}

Question 3¶

Question¶

Given temperature of patient in farenheit as input, print whether the temperature is low, normal, high

normal from 98.2 till 98.8

Testcase 1¶

Input :
98.1

Solution 1¶

Output : Low

Testcase 2¶

Input :
98.5

Solution 2¶

Output : normal

Testcase 3¶

Input :
99.3

Solution 3¶

Output : high

Question¶

Which data type should be used to store temperature of a patient ?

Choices¶

Double
Int
String
long

Solution

Double is used to store the numbers with decimals.

Approach¶

Using conditional statements we check:
- If temperature is < 98.2 print low.
- Else if temperature > 98.5 print high**.
- Else print normal

Pseudeocode¶

public static void main() {
    scn = new Scanner(System.in);

    double temperature = scn.nextDouble();

    if (temperature < 98.2) {
        System.out.print("low");
    } else if (temperature > 98.8) {
        System.out.print("high");
    } else {
        System.out.print("normal");
    }
}

Operators¶

Division¶

Division is denoted by / operator.
Provided below is the output datatype based on dividend and divisor datatype.
- int / int ---> int
- float / int ---> float
- int / float ---> float
- float / float ---> float
- long / int ---> long
- double / float ---> double
- int / long are replacable
- float / double are replacable
To convert a number to float put a f in the ending of it.
To convert a number to double we can write it with .0 in the end.

Example¶

System.out.println(9 / 3) ; // int / int ---> int output would be 3
System.out.println(11 / 3); // int / int ---> int output would be 3
System.out.println(11f / 3) ; // float / int ---> float output would be 3.6666

Multiplication¶

Multiplication is denoted by * operator.
Provided below is the output datatype based on multiplicand and multiplier datatype.
- int * int ---> int
- int * long ---> long
- long * int ---> long
- long * long --->long
- int / float are replacable
- long / double are replacable

Example 1¶

int x = 100000;
int y = 100000;
int z = x * y
System.out.println(z); // prints garbage value

The above code gives garbage value as output but why ?
We can see that when we multiply x and y i.e 100000 * 100000 then output would be 10¹⁰.
Since the range of integer datatype is roughly 10⁹ we would get garbage value due to overflow as we store it in z (int).

Example 2¶

int x = 100000;
int y = 100000;
long z = x * y
System.out.println(z); // prints garbage value

The above code gives garbage value as output but why ? even though we have changed the datatype of z from int ---> long.
We have changed the datatype of z but the according to rules above :-
- int * int ---> int
Therefore we need to explicitly change datatype of the multiplicand or the multiplier to long so that :-
- long * int ---> long
Therefore :-

int x = 100000;
int y = 100000;
long z = (long)x * y;
System.out.println(z); // prints 10000000000

Question¶

What will be the output according to Java :

int a = 100000;
int b = 400000;
long c = (long)(a * b);
System.out.println(c);

Choices¶

Some random number
40000000000
Compilation error
No Output

Solution

First we are doing a * b i.e int * int therefore the output will be int.
Overflow would have already occured before typecasting to long.
Hence the random value is printed.

Operators Continued¶

Modulo¶

Modulo is denoted by % operator.
Gives us the remainder when a is divided by b i.e. a % b = remainder when a is divided by b.

Examples¶

7 % 3 ---> 1
8 % 5 ---> 3
10 % 1 ---> 0
5 % 12 ---> ?
- Answer is 5 by why ?.
- Because 5 % 12 = 12 * 0 + 5 where 5 is dividend, 12 is divisor , 0 is quotient & 5 is remainder.

Question¶

What is the result? System.out.print(17 % 4);

Choices¶

1
4
16
5

Solution

dividend = divisor* quotient + remainder 
=> 17 = 4 * 4 + 1

Question¶

What will be the result of a % b, when b perfectly divides a with no remainder ?

Choices¶

0
b -1
b
a

Solution

dividend = divisor * quotient + remainder 
if dividend is divided perfectly by divisor then the remainder is 0

Question 4¶

Question¶

Given an integer as input, print whether it is even or Odd

Testcase 1¶

Input :
3

Solution 1¶

Output : odd

Testcase 2¶

Input :
6

Solution 2¶

Output : even

Question¶

If a % 2 == 0, what can we say about a ?

Choices¶

even
odd
prime
remainder

Approach¶

Using conditional statements we check:
- If A % 2 == 0 print even.
- Else print odd.

Pseudeocode¶

public static void main() {
    scn = new Scanner(System.in);

    int A = scn.nextInt();
    int B = scn.nextInt();

    if (A % 2 == 0) {
        System.out.print("even");
    } else {
        System.out.print("odd");
    }
}

Question 5¶

Question¶

Q5 : Given an integer as input, print its last digit

Testcase 1¶

Input :
73

Solution 1¶

Output : 3

Testcase 2¶

Input :
651

Solution 2¶

Output : 1

Approach¶

Print A % 10

Pseudeocode¶

scn = new Scanner(System.in);

int A = scn.nextInt();

System.out.print(A % 10);

Operators Continued¶

Relational Operators¶

A > B ---> Checks weather A is greater than B.
A < B ---> Checks weather A is less than B.
A >= B ---> Checks weather A is greater than or equalt to B.
A <= B ---> Checks weather A is less than or equal to B.
A == B ---> Checks weather A is equals B.
A != B ---> Checks weather A is not equal to B.

Logical Operators¶

AND operator is denoted by &&
Truth table is provided below.

A	B	A && B
T	F	F
F	T	F
F	F	F
T	T	T

OR operator is denoted by ||
Truth table is provided below.

A	B	A && B
T	F	T
F	T	T
F	F	F
T	T	T

Question 6¶

Question¶

Q6 : Given units of electricity consumed as an integer input A, print the bill amount. Provided below is the range of electricity consumed and rate at which it is charged:-

[1-50] ---> ₹1
[51-100] ---> ₹2
[101 and beyond] ---> ₹4

Testcase 1¶

Input :
20

Solution 1¶

Output : 20 * 1 = 20

Testcase 2¶

Input :
80

Solution 2¶

Output : 50 * 1 + 30 * 2 = 110

Testcase 3¶

Input :
120

Solution 3¶

Output : 50 * 1 + 50 * 2 + 20 * 4= 230

Warning

Please take some time to think about the solution approach on your own before reading further.....

Pseudeocode¶

public static void main() {

    scn = new Scanner(System.in);
    int A = scn.nextInt();

    if (A >= 1 && A <= 50) {
        System.out.print(A * 1);
    } else if (A >= 51 && A <= 100) {
        System.out.print(50 + (A - 50) * 2);
    } else {
        System.out.print(50 + (50 * 2) + ((A - 100) * 4));
    }
}

Question 7¶

Question¶

Q7 : Given an integer A as input

If it is a multiple of 3, print Fizz
If it is a multiple of 5, print Buzz
If it is a multiple of 3 and 5, print Fizz-Buzz

Testcase 1¶

Input :
5

Solution 1¶

Output : Buzz

Testcase 2¶

Input :
3

Solution 2¶

Output : Fizz

Testcase 3¶

Input :
30

Solution 3¶

Output : Fizz-Buzz

Warning

Please take some time to think about the solution approach on your own before reading further.....

Approach 1¶

public static void main() {

    scn = new Scanner(System.in);
    int A = scn.nextInt();

    if (A % 3 == 0) {
        System.out.print("Fizz");
    } else if (A % 5 == 0) {
        System.out.print("Buzz");
    } else if (A % 3 == 0 && A % 5 == 0) {
        System.out.print("Fizz-Buzz");
    }
}

When we test the above approach on A = 30, we get output as "Fizz"
But correct output would be "Fizz-Buzz", so why the wrong answer ?
Since if-else work in a chained manner the condition A % 3 == 0 is checked first.
Therefore "Fizz" is printed
Correct approach would be to check condition ( A % 3 == 0 && A % 5 == 0 ) first.

Pseudeocode¶

public static void main() {

    scn = new Scanner(System.in);
    int A = scn.nextInt();

    if (A % 3 == 0 && A % 5 == 0) {
        System.out.print("Fizz-Buzz");
    } else if (A % 5 == 0) {
        System.out.print("Buzz");
    } else if (A % 3 == 0) {
        System.out.print("Fizz");
    }
}

If-Else¶

Example¶

If-Else Syntax¶

Question 1¶

Question¶

Testcase 1¶

Solution 1¶

Testcase 2¶

Solution 2¶

Approach¶

Pseudeocode¶

Question 2¶

Question¶

Testcase 1¶

Solution 1¶

Testcase 2¶

Solution 2¶

Approach¶

Pseudeocode¶

public static void main() { scn = new Scanner(System.in); int A = scn.nextInt(); int B = scn.nextInt(); if (A > B) { System.out.print(A + "is bigger"); } else { System.out.print(B + "is bigger"); } } ¶

Question 2 part 2¶

Question¶

Testcase 1¶

Solution 1¶

Testcase 2¶

Solution 2¶

Testcase 2¶

Solution 2¶

Approach¶

Pseudeocode¶

Question 3¶

Question¶

Testcase 1¶

Solution 1¶

Testcase 2¶

Solution 2¶

Testcase 3¶

Solution 3¶

Question¶

Choices¶

Approach¶

Pseudeocode¶

Operators¶

Division¶

Example¶

Multiplication¶

Example 1¶

Example 2¶

Question¶

Choices¶

Operators Continued¶

Modulo¶

Examples¶

Question¶

Choices¶

Question¶

Choices¶

Question 4¶

Question¶

Testcase 1¶

Solution 1¶

Testcase 2¶

Solution 2¶

Question¶

Choices¶

Approach¶

Pseudeocode¶

Question 5¶

Question¶

Testcase 1¶

Solution 1¶

Testcase 2¶

Solution 2¶

Approach¶

Pseudeocode¶

Operators Continued¶

Relational Operators¶

Logical Operators¶

Question 6¶

Question¶

`public static void main() { scn = new Scanner(System.in); int A = scn.nextInt(); int B = scn.nextInt(); if (A > B) { System.out.print(A + "is bigger"); } else { System.out.print(B + "is bigger"); } }`
¶