Exercise #2

Create the following two C programs. NOTE: the use of printf(3) or any other C library function to format or print numbers is not allowed for this exercise. All I/O must be done with the open(2) / read(2) and/or write(2) system calls.

ascii.c:

This program should print an ASCII table that prints the ASCII characters from 0 to 127 in 4 separate columns. Each character should be preceded by its value, which should be printed in decimal by default. The program should accept a command line switch to modify the output of the ASCII values to alternatively print it in binary (-b option), hexadecimal (-h option) or octal (-o option).

Non-printable ASCII characters should be printed as a dot (.). Example output:

    0: '.'        32: ' '         64: '@'         96: '`'
    1: '.'        33: '!'         65: 'A'         97: 'a'
    2: '.'        34: '"'         66: 'B'         98: 'b'
...

hex.c:

This program should print a hex-dump of its input (either from standard input (STDIN_FILENO) or from a file, name provided on the command line.) Example output:

00000000 : 23 69 6E 63 6C 75 64 65  20 3C 75 6E 69 73 74 64 : #include <unistd
00000010 : 2E 68 3E 0A 23 69 6E 63  6C 75 64 65 20 3C 73 79 : .h>.#include <sy
...
000000D0 : 31 34 29 3B 0A 0A 20 20  72 65 74 75 72 6E 20 30 : 14);..  return 0
000000E0 : 3B 0A 7D 0A                                      : ;.}.

The first hex value is the byte offset within the input, then the data read is to be printed as 8 bit hex-values followed by a " : " then the ASCII representation of that data (print a dot (.) if the character is not a printable character or is whitespace, but not an actual space character (i.e. tab, vertical tab, newline or carriage return.)