labs

labs/lab10/Backwards.java

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+// ****************************************************************** 
+// Backwards.java 
+// 
+// Uses a recursive method to print a string backwards. 
+// ****************************************************************** 
+import java.util.Scanner; 
+public class Backwards 
+{ 
+ //-------------------------------------------------------------- 
+ // Reads a string from the user and prints it backwards. 
+ //-------------------------------------------------------------- 
+ public static void main(String[] args) 
+ { 
+ String msg; 
+ Scanner scan = new Scanner(System.in); 
+ System.out.print("Enter a string: "); 
+ msg = scan.nextLine(); 
+ System.out.print("\nThe string backwards: "); 
+ printBackwards(msg); 
+ System.out.println(); 
+ } 
+ 
+ //-------------------------------------------------------------- 
+ // Takes a string and recursively prints it backwards. 
+ //-------------------------------------------------------------- 
+ public static void printBackwards(String s) 
+ { 
+    if (s.isEmpty()) {
+        return;
+    }
+        System.out.print(s.charAt(s.length() - 1)); 
+        printBackwards(s.substring(0, s.length() - 1)); 
+ // Fill in code 
+ } 
+}

labs/lab10/CountLettere.java

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+// **************************************************************** 
+// CountLetters.java 
+// 
+// Reads a words from the standard input and prints the number of 
+// occurrences of each letter in that word. 
+// 
+// **************************************************************** 
+import java.util.Scanner; 
+public class CountLetterse 
+{ 
+ public static void main(String[] args) 
+ { 
+ int[] counts = new int[26]; 
+ Scanner scan = new Scanner(System.in); 
+ //get word from user 
+ System.out.print("Enter a single word (letters only, please): "); 
+ String word = scan.nextLine(); 
+ //convert to all upper case 
+ word = word.toUpperCase(); 
+ //count frequency of each letter in string 
+ for (int i=0; i < word.length(); i++) {
+    try {
+ char current = word.charAt(i);
+    counts[word.charAt(i)-'A']++; 
+    }
+    catch (Exception e){
+        System.out.println("Reason for error:"+"!"+(char)word.charAt(i)+"!");
+    }
+ }
+ //print frequencies 
+ System.out.println(); 
+ for (int i=0; i < counts.length; i++) 
+ if (counts [i] != 0) 
+ System.out.println((char)(i +'A') + ": " + counts[i]); 
+ } 
+} 

labs/lab10/CountLetters.java

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+// **************************************************************** 
+// CountLetters.java 
+// 
+// Reads a words from the standard input and prints the number of 
+// occurrences of each letter in that word. 
+// 
+// **************************************************************** 
+import java.util.Scanner; 
+public class CountLetters 
+{ 
+ public static void main(String[] args) 
+ { 
+ int[] counts = new int[26]; 
+ Scanner scan = new Scanner(System.in); 
+ //get word from user 
+ System.out.print("Enter a single word (letters only, please): "); 
+ String word = scan.nextLine(); 
+ //convert to all upper case 
+ word = word.toUpperCase(); 
+ //count frequency of each letter in string 
+ for (int i=0; i < word.length(); i++) {
+ char current = word.charAt(i);
+ if (current >= 'A' && current <= 'Z') {
+    counts[word.charAt(i)-'A']++; 
+ }
+ }
+ //print frequencies 
+ System.out.println(); 
+ for (int i=0; i < counts.length; i++) 
+ if (counts [i] != 0) 
+ System.out.println((char)(i +'A') + ": " + counts[i]); 
+ } 
+} 

labs/lab10/Power.java

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+// **************************************************************** 
+// Power.java 
+// 
+// Reads in two integers and uses a recursive power method 
+// to compute the first raised to the second power. 
+// **************************************************************** 
+import java.util.Scanner; 
+public class Power 
+{ 
+ public static void main(String[] args) 
+ { 
+ int base, exp; 
+ int answer; 
+ Scanner scan = new Scanner(System.in); 
+ System.out.print("Welcome to the power program! "); 
+ System.out.println("Please use integers only."); 
+ 
+ //get base 
+ System.out.print("Enter the base you would like raised to a power: "); 
+ base = scan.nextInt(); 
+ //get exponent 
+ System.out.print("Enter the power you would like it raised to: "); 
+ exp = scan.nextInt(); 
+ answer = power(base,exp); 
+ System.out.println(base + " raised to the " + exp + " is " + answer); 
+ } 
+ // ------------------------------------------------- 
+ // Computes and returns base^exp 
+ // ------------------------------------------------- 
+ public static int power(int base, int exp) 
+ { 
+ int pow; 
+ if (exp == 0) {
+    pow = 1;
+ } else {
+    pow = base*power(base, exp-1);
+ }
+ return pow;
+ //otherwise set pow to base*base^(exp-1) 
+ //return pow 
+ } 
+}