Description
: Download the lab03-data.dat file and attempt to decipher what the file contains. From the shell, try viewing the file in a text editor. Also try using cat and hexdump to learn what you can about the file.
Any guesses as to what data is stored in this file?
Don’t read any further until you try to decipher what’s in this file!
Next, determine the size (in bytes) of the lab03-data.dat file. To do so, you can use the ls command. If you do not already know the flag to use with ls, check out the man page for ls.
Assume that the lab03-data.dat file contains an array of int variables. Write a C program to read this data file entirely into memory, then display the data using a loop.
To accomplish this, you must call each of the following functions exactly once: calloc(), fopen(), fread(), and fclose(). In other words, allocate enough memory for this file (you can hard-code the number of bytes needed), then use only one call to fread() to read in exactly that number of bytes.
Finally, display the data as follows:
Data point # 0: <int-value>
Data point # 1: <int-value>
Data point # 2: <int-value> …
Data point #183: <int-value>
Data point #184: <int-value>
Data point #185: <int-value>
- Checkpoint 2: Modify your solution for Checkpoint 1 by instead assuming that the given lab03-data.dat file contains an array of unsignedlong variables.
Display the data as follows:
Data point # 0: <unsigned-long-value>
Data point # 1: <unsigned-long-value>
Data point # 2: <unsigned-long-value> …
Data point #90: <unsigned-long-value>
Data point #91: <unsigned-long-value>
Data point #92: <unsigned-long-value>
Did you figure out what this data file contains yet?
Note that we can interpret the raw data however we like, treating it as an array of int values, an array of unsigned long values, a string of printable characters, etc. Only one interpretation turns out to be correct, though.
- Checkpoint 3: For the third and final checkpoint, write a C program to read a text file into memory one line at a time. Use fgets() to accomplish this. And assume a line is no more than 128 bytes long, meaning you can declare a character array buffer as charline[128].
Next, without using square bracket [] notation or any int (or other numeric) variables whatsoever, traverse each line and display each alphanumeric character you find. To accomplish this, use pointer arithmetic and the isalnum() function in ctype.h.
At the end of each line, display the total number of alphanumeric characters found on that line. Use the format shown in the example below. Again, do not use any int or other numeric variables to accomplish this.
Finally, if no alphanumeric characters are found on a given line, do not display anything, not even a blank line.
To test your code, start with small test cases, then download the book-1984.txt file and test with that as input. Your output in this case should start as follows:
PARTONE [7 alnum chars]
Chapter1 [8 alnum chars]
ItwasabrightcolddayinAprilandtheclockswerestrikingthirteen [58 alnum chars] WinstonSmithhischinnuzzledintohisbreastinanefforttoescapethe [60 alnum chars] vilewindslippedquicklythroughtheglassdoorsofVictoryMansions [59 alnum chars] thoughnotquicklyenoughtopreventaswirlofgrittydustfromentering [61 alnum chars] alongwithhim [12 alnum chars] …
HINT: Use pointer arithmetic to achieve this checkpoint.
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