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Author: learnwithrt

CalculateArea.java

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+//#include<stdio.h> - printf is in standard input output header file
+import java.util.Scanner;//utilities
+class CalculateArea{
+	public static void main(String args[]){
+		double radius;//floating type values
+		double area;
+		//read input from user
+		Scanner scan=new Scanner(System.in);
+		radius=scan.nextDouble();
+		area=Math.PI * radius * radius;
+		//append radius with the string "Area is"
+		System.out.println("Area is"+area);
+		//System.out object to print(output) something
+	}
+}

Chapter 3.rar

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+class CommandInputDemo{
+	//args is command line arguments which are passed to the program before the program starts executing
+	public static void main(String args[]){
+		//index -0
+		System.out.println("Welcome "+args[0]);//Name
+		System.out.println("From "+args[1]);//class
+		System.out.println("In "+args[2]);//School Name
+	}
+}

Chapter 4.rar

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+class IncrementDecrementDemo{
+	public static void main(String a[]){
+		int i=5;
+		int j=6;
+		int k=i++;//6
+		//1. Use the value
+		//2. Change the value
+		System.out.println(k);//6
+		k=++j;//pre increment 7
+		//1. Change the value
+		//2. Use the value
+		System.out.println(k);//7
+		//7+6
+		System.out.println(++i+--j);//13
+	}
+}

Chapter 5.rar

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+import java.lang.*;//import all classes from package java.lang
+import java.util.Scanner;
+class MathDemo{
+	public static void main(String agrs[]){
+		int a=10;
+		int b=4;
+		//Print 10 raised to a power of 4
+		System.out.println(Math.pow(a,b));//10*10*10*10
+		System.out.println(Math.pow(b,a));//4^10
+		//Math is in package java.lang
+		//Scanner is in package java.util
+		//java.lang package is imported by default in all your programs
+		float f=10.5f;
+		float fl=10.6F;
+		int x=10;
+		int y=20;
+		x+=30;	//x=x+30;
+		y/=5;	//y=y/5;
+		System.out.println(x);
+		System.out.println(y);
+
+
+	}
+}

Chapter 6.rar

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+class OpDemo{
+	public static void main(String args[]){
+		int a=10;
+		int b=20;
+		System.out.println("Addition "+(a+b));//java will append them
+		System.out.println("Subtraction "+(a-b));
+		System.out.println("Multiplication "+(a*b));
+		System.out.println("Division "+(a/b));//0
+		//Type casting- cast an integer to a float
+		//treat b as a float value
+		System.out.println("Division "+(a/(float)b));//0.5
+		//Modulus- Remainder
+		System.out.println("Modulus "+(20%13));//7
+		System.out.println("Divide "+(20/13));//7
+	}
+}