| 9.8.8. Read an unknown number of integers from a file | ||
|---|---|---|
 | 9.8. Activities |  |
| 9.8.8. Read an unknown number of integers from a file | ||
|---|---|---|
| | 9.8. Activities | |
For this activity you may start with the source code
from fread_fixed_integers.c, which read integers from a file. Copy
that code in the folder fread_variable in your
shared folder.
Section 3 from Reading and writing with files
Files in Linux are simply a sequence of bytes. If a file
stores data of arbitrary size, then we should know the amount of data to
read to give it as a parameter to the function fread. There are
several ways to solve this problem, and one of them consists of include as
first element an integer with the size of data size. This way, the first
data read is an integer indicating how much data is stored in the next
positions. The following figure shows this technique for a file with 5
integers.
SIZE|INTEGER_0|INTEGER_1|INTEGER_2Modify the program fread_fixed_integers.c, and call it
fread_variable_integers.c. It should read the integers from
a file with that structure (a binary file with numbers stored in
consecutive positions, being the first number the number of
elements):
Your program should read the size and allocate memory with
the malloc function. Do not forget of using the
free function to free the allocated memory before the end of
your program.
Check the program with these data files:
fich_10_enteros and fich_enteros
that you can find in the fread_variable sub-folder in
your shared folder.
Upload the program to the folder
fread_variable in your workspace in
Subversion.
| |  | |
| 9.8.7. Read an unknown number of words from a file |  | 9.8.9. Read a line by keyboard and write in file |