Counters
There are a number of times in computer programming where the user needs to determine the number of times a certain event occurs.
Examples:
- Counting the number of times a person enters a number (in order to find the average)
- Determining how many rolls of two dice were needed before a 6 was rolled
- Counting the number of times “heads” was flipped when flipping a coin 100 times.
The counter statement in programming looks like:
counter = counter +1
or
c = c+ 1
Even though this is not a valid equation in Mathematics, it is completely valid in programming.
The equal sign is interpreted as “is replaced by”.
Therefore c = c +1 forces the computer to:
- go get the value of c from memory
- add 1 to the value of c
- re-store the value of c in the same memory location
i.e. it takes the current value of ‘c’ in memory and increases it by one.
The counter statement is placed in a program immediately after the process that is being counted.
Totals
The total statement is very similar to the counter statement, but instead of increasing the counter variable by 1, the total statement increases the total by whatever needs to be added to the total.
The format of the total statement is:
total = total + num (if the total is to be increased by the value of num)
agetotal = agetotal + age
Example Program: The following program will allow the user to enter numbers one after another until a zero is entered. The program will find the average of all the numbers that were entered.
dim total as integer, numcount as integer, num as integer, average as single
total = 0
numcount = 0
do
input “Enter a number: “, num
if num = 0 then exit do
total = total + num
numcount = numcount +1
loop
average = total / numcount
print using “the average of the numbers is ###.#”; average
