You may find the page on accumulating variables useful:
[http://progzoo.net/tut.cgi/java/ht70Tech/100Acc.xml Using an accumulator.]
How many countries in Asia?
In this example we use an accumulator to count the countries in Africa.
acc shows up three times:
acc is set to zero at the start.
- Every time we encounter Africa we increment
- After the loop has completed
acccontains the value
we want - so we print it.
Change the program so that it counts the countries of Asia. Do NOT include the countries of Southeast Asia.
The accumulating variable is a very common trick in programming.
The accumulator builds up the values - so that it is "right-so-far".
For example in this program
acc always holds the number of
countries in Africa in the lines that have been read so far.
How many big countries?
Count the number of countries with an area of more than 1500000.
Produce a numbered list of countries:
1 Afghanistan 2 Albania 3 Algeria ... 262 Zimbabwe
Use three character spaces for the number and put a single space after it.
Country number 42.
Print the name of country number 42