Array exercises

1. Write a program that searches an array. For this you will use an inline initialization of an array (we'll do this together); then you will ask the user for a target value. Then you will search for this value in the array, and you will print ALL positions where you find it. The output should look as follows:
   • (a) First, make your output as below:

     Here is the array you'll be woking with: 3 2 5 2 7 4 3 5
     
     Enter target value: 3
     Target 3 occurs in the list at position: 0 
     Target 3 occurs in the list at position: 6
     Goodbye.
     

     or

     Here is the array you'll be woking with: 3 2 5 2 7 4 3 5
     
     Enter target value: 8
     Goodbye.
     

   • (b) Modify your solution above so that it keeps track whether the target is found or not, in order to be able to print a "not found" message at the end (If the target is found, nothing changes).

     Here is the array you'll be woking with: 3 2 5 2 7 4 3 5
     
     Enter target value: 8
     Target 8 is not in the list.
     Goodbye.
     

     Hint: One way to do it is to use a variable that counts the number of times the target is found. Another way is to use a boolean variable that keeps track whether the target has been found or not; maintain this variable through the search loop.

      
     //this variable keeps track whether the target has been found or not
     boolean isFound; 
     
     //initially we have not found it yet
     isFound = false;
     
     
     //search loop
     while (..) {
     
          //if we find target set isFound to true
     }
     //at the end of the loop isFound should be true if and only if 
     //the target has been found at least once
     
     
     if (isFound == false) {
         //tell the user the target is not in the list
     }
     

   • (c) Refine your solution further so that it displays the results as below:

     Here is the array you'll be woking with: 3 2 5 2 7 4 3 5
     
     Enter target value: 3
     Target 3 occurs in the list at position: 0 6
     Goodbye.
     

     or

     Here is the array you'll be woking with: 3 2 5 2 7 4 3 5
     
     Enter target value: 8
     Target 8 is not in the list.
     Goodbye.
     

     Hint: use your boolean variable isFound from part (b). Based on it you can figure out if it is the first time you find the target, or not.

      
     //this variable keeps track whether the target has been found or not
     boolean isFound; 
     
     //initially we have not found it yet
     isFound = false;
     
     
     //search loop
     while (..) {
           //compare target to element i
           //if we find target then
                  //if its the first time we find it then 
                         //print "The target occurs at position: " 
                         //set isFound to true
                  //print position 
           //increment loop counter
     }
     //at the end of the loop isFound should be true if and only if 
     //the target has been found at least once
     
     
     if (isFound == false) {
         //tell the user the target is not in the list
     }
     

2. Modify the search program so that it repeatedly asks the user whether she wants to search the array. If the user says yes, it then asks for a target, and prints all positions where it finds the target, as above. If the user says no, then it terminates.

   Here is the array you'll be woking with: 3 2 5 2 7 4 3 5
   
   Do you want to search? (Press y for yes, n for n): y
   Enter target value: 3
   Target 3 occurs in the list at position 0 6
   
   Do you want to search? (Press y for yes, n for n): y
   Enter target value: 5
   Target 5 occurs in the list at position 2 7
   
   Do you want to search? (Press y for yes, n for n): y
   Enter target value: 9
   Target 9 is not in the list 
   
   Do you want to search? (Press y for yes, n for n): n
   Goodbye.
   

3. Write a program that reads an array from the user, and then computes and prints out the largest number in the array, and its position.

   What size will your array be? 5
   Enter element 0:  2
   Enter element 1:  8
   Enter element 2:  5
   Enter element 3:  4
   Enter element 4:  -1
   Thank you.
   The largest number is 8 at position 1.
   Goodbye.
   

   If the numbers in the list (array) are not unique, the largest number could occur more than once. Would your algorithm find the first occurence? The last? Explain.