Programming in C

Exercises
297
Exercises
1. Type in and run the four programs presented in this chapter. Compare the output
produced by each program with the output presented after each program in the
text.
2. Write a program that determines whether your particular computer performs an
arithmetic or a logical right shift.
3. Given that the expression ~0 produces an integer that contains all 1s, write a function
called int_size that returns the number of bits contained in an int on your
particular machine.
4. Using the result obtained in exercise 3, modify the rotate function from Program
12.4 so that it no longer makes any assumptions about the size of an int.
5. Write a function called bit_test that takes two arguments: an unsigned int and
a bit number n.Have the function return 1 bit number n if it is on inside the
word,and 0 if it is off. Assume that bit number 0 references the leftmost bit inside
the integer. Also write a corresponding function called bit_set that takes two
arguments: an unsigned int and a bit number n.Have the function return the
result of turning bit n on inside the integer.
6. Write a function called bitpat_search that looks for the occurrence of a specified
pattern of bits inside an unsigned int.The function should take three arguments
and should be called as shown:
bitpat_search (source, pattern, n)
The function searches the integer source,starting at the leftmost bit, to see if the
rightmost n bits of pattern occur in source. If the pattern is found, have the
function return the number of the bit at which the pattern begins, where the leftmost
bit is bit number 0. If the pattern is not found, then have the function return
–1.So, for example, the call
index = bitpat_search (0xe1f4, 0x5, 3);
causes the bitpat_search function to search the number 0xe1f4 ( = 1110 0001
1111 0100 binary ) for the occurrence of the three-bit pattern 0x5 (= 101 binary).
The function returns 11 to indicate that the pattern was found in the source
beginning with bit number 11.
Make certain that the function makes no assumptions about the size of an int (see
exercise 3 in this chapter).
7. Write a function called bitpat_get to extract a specified set of bits. Have it take
three arguments: the first an unsigned int, the second an integer starting bit
number, and the third a bit count. Using the convention that bit numbering starts