Counting Characters

Count.java contains the skeleton of a program to read in a string (a sentence or phrase) and count the number of blank spaces in the string. The program currently has the declarations and initializations and prints the results. All it needs is a loop to go through the string character by character and count (update the countBlank variable) the characters that are the blank space. Since we know how many characters there are (the length of the string) we use a count controlled loop.

1. Add the while loop to the program. Inside the while loop you need to access each individual characterthe charAt method of the String class lets you do that. The assignment statement

ch = phrase.charAt(i);

assigns the variable ch (type char) the character that is in index i of the String phrase. In your for loop you can use an assignment similar to this (replace i with your loop control variable if you use something other than i). NOTE: You could also directly use phrase.charAt(i) in your if (without assigning it to a variable).

2. Test your program on several phrases to make sure it is correct.

3. Now modify the program so that it will count several different characters, not just blank spaces. To keep things relatively simple we'll count the a's, e's, r's, s's, t's (upper and lower case) in the string. You need to declare and initialize five additional counting variables (e.g. countA and so on). Your current if could be modified to cascade but another solution is to use a switch statement. Replace the current if with a switch that accounts for the 11 cases we want to count (upper and lower case a, e, r, s, t, and blank spaces). The cases will be based on the value of the ch variable. The switch starts as followscomplete it.

switch (ch)

{

case 'a':

case 'A': countA++ ;

break;

case ....

}

Note that this switch uses the "fall through" feature of switch statements. If ch is an 'a' the first case matches and the switch continues execution until it encounters the break hence the countA variable would be incremented.

4. Add statements to print out all of the counts.

5. It would be nice to have the program let the user keep entering phrases rather than having to restart it every time. To do this we need another loop surrounding the current code. That is, the current loop will be nested inside the new loop. Add an outer while loop that will continue to execute as long as the user does NOT enter the phrase quit. Modify the prompt to tell the user to enter a phrase or quit to quit. Note that all of the initializations for the counts should be inside the while loop (that is we want the counts to start over for each new phrase entered by the user). All you need to do is add the while statement (and think about the placement of your reads so the loop works correctly). Be sure to go through the program and properly indent after adding codewith nested loops the inner loop should be indented.