Learn to Program with C_ Learn to Program using the Popular C Programming Language ( PDFDrive )

Chapter 5 ■ Programs with Repetition Logic
We point out that we could write all our programs without using increment, decrement,
or the special assignment operators. However, sometimes, they permit us to express certain
operations more concisely, more conveniently, and, possibly, more clearly.
5.6 Find Largest
Suppose we want to write a program that works as follows: the user will type some numbers and
the program will find the largest number typed. The following is a sample run of the program
(underlined items are typed by the user):
Enter a number (0 to end): 36
Enter a number (0 to end): 17
Enter a number (0 to end): 43
Enter a number (0 to end): 52
Enter a number (0 to end): 50
Enter a number (0 to end): 0
The largest is 52
The user will be prompted to enter numbers, one at a time. We will assume that the numbers
entered are all positive integers. We will let the user enter as many numbers as she likes. However,
in this case, she will need to tell the program when she wishes to stop entering numbers. To do so,
she will type 0.
Finding the largest number involves the following steps:
• Choose a variable to hold the largest number; we choose bigNum.
• Initialize bigNum to a very small value. The value chosen should be such that
no matter what number is entered, its value would be greater than this initial
value. Since we are assuming that the numbers entered would be positive,
we can initialize bigNum to 0.
• As each number (num, say) is entered, it is compared with bigNum; if num is
greater than bigNum, then we have a bigger number and bigNum is set to this
new number.
• When all the numbers have been entered and checked, bigNum will contain
the largest one.
These ideas are expressed in the following algorithm:
set bigNum to 0
get a number, num
while num is not 0 do
if num is bigger than bigNum, set bigNum to num
get a number, num
endwhile
print bigNum
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