Question

3. (24%) Write the following functions. You MUST use recursion for credit. You may use the string library functions: indexing, lengthO, +, and substr(int n) (recall that substr(n) returns a string with all but the first n characters). (a) string alternate(string s): returns a string that contains every other element of s starting at the beginning. For example, alternate( 'dog' ') ''dg'' (b) string uc(string s): returns a string that is the same as s except that every upper case character is replaced with a "UC" Hint: assume you have the uc of the string's tail. (c) string uc2(string s, string repl): same as above, but replace it with repl instead of "UC"

Answer 1

Hi Student,

Please find below the solutions.

a.

private static String alternate(String str) {

String res = "";

for(int i=0; i<str.length();i++){

res+=str.charAt(i);

i++;

}

return res;

}

b.

private static String uc(String str1) {

String res = "";

for(char c : str1.toCharArray()) {

if(Character.isUpperCase(c)) {

res+="UC";

}

else{

res+=c;

}

}

return res;

}

c.

private static String uc2(String str1) {

String res = "";

for(char c : str1.toCharArray()) {

if(Character.isUpperCase(c)) {

res+="repl";

}

else{

res+=c;

}

}

return res;

}

Here is a complete program that you can run to see how exactly it is working.

import java.util.Scanner;

public class TriangleNumber {

public static void main(String[] args) {

String str = "dog";

System.out.println(alternate(str));

String str1 = "UpperCase";

System.out.println(uc(str1));

  

String str2 = "UpperCase";

System.out.println(uc2(str2));

}

private static String uc(String str1) {

String res = "";

for(char c : str1.toCharArray()) {

if(Character.isUpperCase(c)) {

res+="UC";

}

else{

res+=c;

}

}

return res;

}

private static String uc2(String str1) {

String res = "";

for(char c : str1.toCharArray()) {

if(Character.isUpperCase(c)) {

res+="repl";

}

else{

res+=c;

}

}

return res;

}

private static String alternate(String str) {

String res = "";

for(int i=0; i<str.length();i++){

res+=str.charAt(i);

i++;

}

return res;

}

}

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