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

Chapter 8 ■ Arrays
16. Write a function removethat, given a string str and a character c,
removes all occurrences of c from str. For example, if str contains
"brother,"remove(str,'r') should change str to "bothe."
17. Write a program to read English words and their equivalent Spanish words into
two arrays. Request the user to type several English words. For each, print the
equivalent Spanish word. Choose a suitable end-of-data marker. Modify the
program so that the user types Spanish words instead.
18. The number 27472 is said to be palindromic since it reads the same forwards or
backwards. Write a function that, given an integer n, returns 1 if n is palindromic
and 0 if it is not.
19. Write a program to find out, for a class of students, the number of families with
1, 2, 3, ... up to 8 or more children. The data consists of the number of children in
each pupil’s family, terminated by 0. (Why is 0 a good value to use?)
20. A survey of 10 pop artists is made. Each person votes for an artist by specifying
the number of the artist (a value from 1 to 10). Write a program to read the names
of the artists, followed by the votes, and find out which artist is the most popular.
Choose a suitable end-of-data marker.
21. The children’s game of ‘count-out’ is played as follows. n children (numbered 1 to n)
are arranged in a circle. A sentence consisting of m words is used to eliminate one
child at a time until one child is left. Starting at child 1, the children are counted
from 1 to m and the m th child is eliminated. Starting with the child after the one
just eliminated, the children are again counted from 1 to m and the m th child
eliminated. This is repeated until one child is left. Counting is done circularly and
eliminated children are not counted. Write a program to read values for n (assumed
<= 100) and m (> 0) and print the number of the last remaining child.
22. The prime numbers from 1 to 2500 can be obtained as follows. From a list of the
numbers 1 to 2500, cross out all multiples of 2 (but not 2 itself). Then, find the next
number (n, say) that is not crossed out and cross out all multiples of n (but not n).
Repeat this last step provided that n has not exceeded 50 (the square root of 2500).
The numbers remaining in the list (except 1) are prime. Write a program that uses
this method to print all primes from 1 to 2500. Store your output in a file called
primes.out. This method is called the Sieve of Eratosthenes, named after the
Greek mathematician, geographer, and philosopher.
23. There are 500 light bulbs (numbered 1 to 500) arranged in a row. Initially, they are
all OFF. Starting with bulb 2, all even numbered bulbs are turned ON. Next, starting
with bulb 3, and visiting every third bulb, it is turned ON if it is OFF, and it is turned
OFF if it is ON. This procedure is repeated for every 4th bulb, then every 5h bulb,
and so on up to the 500th bulb. Write a program to determine which bulbs are OFF
at the end of the above exercise.
There is something special about the bulbs that are OFF. What is it? Can you explain
why it is so?
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