H
OMEWORK
1 ECS 30-A — S
PRING
2002
Version of April 5, 2002 8:26 am Page 1 of 2
Homework 1
Due Date:
Friday, April 12, 2002
Points
: 100
UNIX System
1. (
10 points
) Give a one-line UNIX command that capitalizes the vowels (the letters “a”, “e”, “i”, “o”, and “u”) in
a file.
2. (
10 points
) Use a UNIX program to compute the remainder of 7358^349 when divided by 1345.
C Programming
3. (
25 points
) Write a program that asks the user to enter two integers, then calculates and displays their greatest
common divisor (GCD). The input and output must look like this:
Enter two integers: 14 49
The GCD of 14 and 49 is 7.
where “14” and “49” are numbers the user types and “7” is the corresponding GCD. Be sure to check the input
for validity, and terminate the program when the user types an end of file character! (
Hint
: The classic algorithm
for computing the GCD, known as Euclid’s Algorithm, goes as follows. Let
m
and
n
be variables containing the
two numbers. Divide
m
by
n
. Save the divisor in
m
, and save the remainder in
n
. If
n
is 0, stop;
m
contains the
GCD. Otherwise, repeat the process, starting with the division of
m
by
n
.)
4. (
30 points
) Every computer is limited in the amount of precision it can represent for floating-point numbers. At
some point, where
epsilon
is very small, the following expression will be true:
1.0 == 1.0 + epsilon
Write a program to find the largest value of
epsilon
on your computer. Note that the value of
epsilon
may be dif-
ferent for floats and doubles. Find both values (and the value for long doubles if your compiler supports them).
Also, use 1.0 rather than 0.0 to test
epsilon
because most computers have special hardware instructions for han-
dling zero arithmetic. (
Hint
: for
gcc
(1), a long double is the same as a double.)
Debugging
5. (
25 points
) On the class web page is the source for a C program named
vis.c
that reads characters from the stan-
dard input and prints them on the standard output after expanding any non-printing characters to their C character
escape sequence.
The relevant characters, and the C escape sequences to be printed when those characters are encountered, are:
The “anything else” entry means that any non-printing character other than the ones named in the table is to be
printed as a sequence of three octal digits preceded by a backslash. When the escape sequence for a newline is
printed, the program is to skip to the next line.
character print as character print as
newline \n backslash \\
horizontal tab \t vertical tab \v
backspace \b carriage return \r
form feed \f bell \a
NUL \0 anything else \ooo
