Basic Computation

Author: sharaf-qeshta

chapter_02/Exercise_02_01/Exercise_02_01.java

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+package chapter_02;
+
+import java.util.Scanner;
+
+/**
+ * 1. Write a program that demonstrates the approximate nature of double
+ * values by performing the following tasks:
+ * • Use Scanner to read a double value x.
+ * • Compute 5.0 * x and store the result in y.
+ * • Display x, y, and the sum of x and y.
+ * • Divide 5.0 from x and store the result in z. Display the value of z.
+ * Try your program with values of x that range from 2e-11 to 2e11.
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_01
+{
+    public static void main(String[] args)
+    {
+        /*
+        * Enter a double value x: 2e11
+        * X = 2.0E11
+        * Y = 1.0E12
+        * X + Y = 1.2E12
+        * Z = 4.0E10
+        * */
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.print("Enter a double value x: ");
+        double x = scanner.nextDouble();
+
+        double y = x * 5.0;
+
+        System.out.println("X = " + x);
+        System.out.println("Y = " + y);
+        System.out.println("X + Y = " + (x + y));
+
+        double z = x/5.0;
+        System.out.println("Z = " + z);
+    }
+}

chapter_02/Exercise_02_02/Exercise_02_02.java

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+package chapter_02;
+
+import java.util.Scanner;
+
+/**
+ * 2. Write a program that demonstrates type casting of double values by
+ * performing the following tasks:
+ * • Use Scanner to read a floating-point value x.
+ * • Type cast x to an int value and store the result in y.
+ * • Display x and y clearly labeled.
+ * • Type cast x to a byte value and store the result in z.
+ * • Display x and z clearly labeled.
+ * Try your program with positive and negative values of x that range in
+ * magnitude from 2e-11 to 2e11. What can you conclude?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_02
+{
+    public static void main(String[] args)
+    {
+        /*
+        * Enter a double value x: 56.256
+        * X = 56.256
+        * Y = 56
+        * X = 56.256
+        * Z = 56
+        * */
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.print("Enter a double value x: ");
+        double x = scanner.nextDouble();
+
+        int y = (int) x;
+        System.out.println("X = " + x);
+        System.out.println("Y = " + y);
+
+        byte z = (byte) x;
+        System.out.println("X = " + x);
+        System.out.println("Z = " + z);
+    }
+}

chapter_02/Exercise_02_03/Exercise_02_03.java

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+package chapter_02;
+
+import java.util.Scanner;
+
+/**
+ * 3. Write a program that demonstrates the operator ++ by performing the
+ * following tasks:
+ * • Use Scanner to read an integer value x.
+ * • Compute x++ and store the result in y.
+ * • Display x and y clearly labeled.
+ * • Compute ++x and store the result in z.
+ * • Display x and z clearly labeled.
+ * Try your program with positive and negative values of x. What can you
+ * conclude about pre- and post-increment?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_03
+{
+    public static void main(String[] args)
+    {
+        /*
+        * Enter an integer value x: 12
+        * X = 13
+        * Y = 12
+        * X = 14
+        * Z = 14
+        * */
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.print("Enter an integer value x: ");
+        int x = scanner.nextInt();
+
+        int y = x++;
+        System.out.println("X = " + x);
+        System.out.println("Y = " + y);
+
+        int z = ++x;
+        System.out.println("X = " + x);
+        System.out.println("Z = " + z);
+    }
+}

chapter_02/Exercise_02_04/Exercise_02_04.java

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+package chapter_02;
+
+
+/**
+ * 4. If u = 2, v = 3, w = 5, × = 7, and y = 11, what is the value of each of the
+ * following expressions, assuming int variables?
+ * • u + v * w + ×
+ * • u + y % v * w + ×
+ * • u++ / v + u++ * w
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_04
+{
+    // u + v * w + ×
+    /*
+     * first compute v * w = 15
+     * then
+     * 2 + 15 + 7 = 24
+     * */
+
+    // u + y % v * w + ×
+    /*
+    * since % * have the same preceding we will start
+    * from left to right first compute y % v then multiply the result by w
+    * 11 % 3 = 2
+    * 2 * 5 = 10
+    * 2 + 10 + 7 = 19
+    * */
+
+    // u++ / v + u++ * w
+    /*
+    * 2 / 3 + 3 * 5
+    * 2/3 = 0
+    * 3 * 5 = 15
+    * 0 + 15 = 15
+    * */
+}

chapter_02/Exercise_02_05/Exercise_02_05.java

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+package chapter_02;
+
+
+import java.util.Scanner;
+
+/**
+ * 5. What changes to the ChangeMaker program in Listing 2.3 are necessary if it
+ * also accepts coins for one dollar and half a dollar?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_05
+{
+    public static void main(String[] args) {
+        int amount, originalAmount,
+                dollars, halves, quarters, dimes, nickels, pennies; // here
+
+        System.out.println("Enter a whole number from 1 to 99.");
+        System.out.println("I will find a combination of coins");
+        System.out.println("that equals that amount of change.");
+        Scanner keyboard = new Scanner(System.in);
+        amount = keyboard.nextInt();
+        originalAmount = amount;
+        // here
+        dollars = amount / 100;
+        amount = amount % 100;
+        halves = amount / 50;
+        amount = amount % 50;
+
+        quarters = amount / 25;
+        amount = amount % 25;
+        dimes = amount / 10;
+        amount = amount % 10;
+        nickels = amount / 5;
+        amount = amount % 5;
+        pennies = amount;
+        System.out.println(originalAmount +
+                " cents in coins can be given as:");
+
+        // here
+        System.out.println(dollars + " dollars");
+        System.out.println(halves + " halves");
+
+        System.out.println(quarters + " quarters");
+        System.out.println(dimes + " dimes");
+        System.out.println(nickels + " nickels and");
+        System.out.println(pennies + " pennies");
+    }
+}

chapter_02/Exercise_02_06/Exercise_02_06.java

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+package chapter_02;
+
+
+/**
+ * 6. If the int variable × contains 10, what will the following Java statements
+ * display?
+ * System.out.println("Test 1" + × * 3 * 2.0);
+ * System.out.println("Test 2" + × * 3 + 2.0);
+ * Given these results, explain why the following Java statement will not
+ * compile:
+ * System.out.println("Test 3" + × * 3 − 2.0);
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_06
+{
+    // System.out.println("Test 1" + × * 3 * 2.0);
+    /*
+    * 10 * 3 * 2.0 and concatenate it with Test 1
+    * so the output will be
+    * Test 160.0
+    * since 10 * 3 * 2.0 = 60.0
+    * */
+
+    // System.out.println("Test 2" + × * 3 + 2.0);
+    /*
+    * same as the previous one
+    * Test 260.0
+    * */
+
+    // System.out.println("Test 3" + × * 3 − 2.0);
+    /*
+    * as we know operations have precedence so
+    * x * 3 will be evaluated fine
+    * we still have "Test 3" + 30 - 2.0
+    * because of the precedence  we start from left to right
+    * we will evaluate "Test 3" + 30 then
+    * we will end up with a new string  "Test 330"
+    * as you know we cannot apply subtraction to strings
+    * in java
+    * */
+}

chapter_02/Exercise_02_07/Exercise_02_07.java

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+package chapter_02;
+
+
+/**
+ * 7. Write some Java statements that use the String methods lastIndexOf and
+ * substring to find the last word in a string. We define word to be a string of
+ * characters that does not include whitespace. For example, the last word of the
+ * string
+ * "Hello, my good friend!"
+ * is the string "friend!"
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_07
+{
+    public static void main(String[] args)
+    {
+        String phrase = "Hello, my good friend!";
+        String lastWord = phrase.substring(phrase.lastIndexOf(" ")+1);
+
+        /* The last word in the phrase "Hello, my good friend!" is "friend!" */
+        System.out.println("The last word in the phrase \"" + phrase + "\" is \"" + lastWord + "\"" );
+    }
+}

chapter_02/Exercise_02_08/Exercise_02_08.java

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+package chapter_02;
+
+
+/**
+ * 8. Repeat the previous exercise, but find the second last word in the string
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_08
+{
+    public static void main(String[] args)
+    {
+        String phrase = "Hello, my good friend!";
+        String lastWord = phrase.substring(phrase.lastIndexOf(" "));
+        String newPhrase = phrase.replace(lastWord, "");
+        lastWord = newPhrase.substring(newPhrase.lastIndexOf(" ")+1);
+
+        /* The second last word in the phrase "Hello, my good friend!" is "good" */
+        System.out.println("The second last word in the phrase \"" + phrase + "\" is \"" + lastWord + "\"" );
+    }
+}

chapter_02/Exercise_02_09/Exercise_02_09.java

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+package chapter_02;
+
+
+/**
+ * 9. What does the following Java statement display?
+ * System.out.println("\"\\Release\"\\\tYour\n\\\'Stress\'\\\"\robot\"");
+ * What is the significance of \R and \r here?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_09
+{
+    // "\Release"\  Your
+    // obot"
+
+    // \r means back to the beginning of the current line
+    // \R does not mean anything
+}

chapter_02/Exercise_02_10/Exercise_02_10.java

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+package chapter_02;
+
+
+/**
+ * 10. Write a single Java statement that will display the words Alice, In, and
+ * WonderLand, adding tab between the words and the third word within
+ * double quotes.
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_10
+{
+    public static void main(String[] args)
+    {
+        System.out.println("Alice,\tIn,\tand\t\"Wonderland\"");
+    }
+}

chapter_02/Exercise_02_11/Exercise_02_11.java

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+package chapter_02;
+
+/**
+ * 11. What does the Java code
+ * Scanner keyboard = new Scanner(System.in);
+ * System.out.println("Enter a value");
+ * double val = keyboard.nextDouble();
+ * System.out.println("Value entered is " + val);
+ * display when the keyboard input is 4pi?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_11
+{
+    // Error the programme will deal with 4pi as string
+    // so you enter a string while the programme expect a double value
+}

chapter_02/Exercise_02_12/Exercise_02_12.java

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+package chapter_02;
+
+
+/**
+ * 12. What does the Java code
+ * Scanner keyboard = new Scanner(System.in);
+ * keyboard.useDelimiter("m");
+ * System.out.println("Enter a string.");
+ * String string1 = keyboard.next();
+ * String string2 = keyboard.next();
+ * System.out.println("String1 is " + string1);
+ * System.out.println("String2 is " + string2);
+ * display when the keyboard input is
+ * Dream
+ * Think
+ * Imagine
+ *
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_02_12
+{
+    // String1 is Drea
+    // String2 is Think I
+}