Accumulate over a File

In this example we use an accumulator to count the countries in Africa.

Notice that acc shows up three times:

The accumulator acc is set to zero at the start.

• Every time we encounter Africa we increment acc.
• After the loop has completed acc contains 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.

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.

Print the name of country number 42

Calculate the total area of the world.

This time we add to the accumulator each time. We can use either of the statements below:

acc = acc + area;

acc += area;

Calculate the total population of the world.

The answer - at a little over 6 billion will be too large for and int. Use a long instead.

Calculate the total GDP of the countries of Africa.

Calculate the total GDP of the western world. Include the regions "North America", "Europe" and "Oceania" as the western world.