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Full Discussion: Malloc problem with fread() to read file to structure in C
Top Forums Programming Malloc problem with fread() to read file to structure in C Post 302887657 by yifangt on Monday 10th of February 2014 04:03:39 AM
Old 02-10-2014
Thanks Don!
Two things I was trying to catch:
1) Read the file into linked list, each line for a node which is a structure with two members: roll_num (int) and name (char array or char *); This is similar to my old post when I tried to parse file as 4-line record, i.e. every four line is a record.
2) Save the linked list to a new file.
For point 1), the problem with my code is the first and last record (i.e. nodes) of the linked list were always wrong---printed incorrectly.
Quote:
808464433 1 Angola //cf 10001 Angola
?x.?0010 Ja1 //cf 10010 Jamaica
For Point 2) my code was just not working at all, so that the corresponding part Line 30 ~ Line 40 were commented out.
For point 1) an extra question in my mind is using char pointer instead of char array, how to accomplish the same job? as pointer is still a big challenge for me, especially when dynamic memory allocation is related.
I am trying to understand the FILE stream and memory allocation with malloc() for file manipulation. (The next step is to do some manipulation of each node, say change each roll_num, modify the name, or add another member for each node, etc. But I am not able to do it at this moment.)

Since the size of your current structure is about 132 bytes long (4 byte int, 120 byte char array, and 8 byte pointer), you are reading the 1st 132 bytes from your input file into the first element of your linked list,
Yes, that's what I was trying. I had thought of wrong mem allocation, so that I was thinking to use char pointer for name instead of char array for dynamic memory allocation. I know I am too far from this point.

So, lines 30 to 40 are just a single comment to the C compiler and no code is being executed in this comment.
Yes, I did that on purpose because it did not work.

If you verify that what I listed above is what you're trying to do,
Yes, that's what I was trying to do!

I'll try to come up with an example that shows how to do that in the next couple of days.
Great! Thank you very much for your time.
Last edited by yifangt; 02-10-2014 at 05:14 AM..
 

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LEARN ABOUT OPENDARWIN

set_color

set_color(1)							       fish							      set_color(1)

NAME

       set_color - set_color - set the terminal color

set_color - set the terminal color
   Synopsis
       set_color [-v --version] [-h --help] [-b --background COLOR] [COLOR]

   Description
       Change the foreground and/or background color of the terminal. COLOR is one of black, red, green, brown, yellow, blue, magenta, purple,
       cyan, white and normal.

       o -b, --background Set the background color

       o -c, --print-colors Prints a list of all valid color names

       o -h, --help Display help message and exit

       o -o, --bold Set bold or extra bright mode

       o -u, --underline Set underlined mode

       o -v, --version Display version and exit

       Calling set_color normal will set the terminal color to whatever is the default color of the terminal.

       Some terminals use the --bold escape sequence to switch to a brighter color set. On such terminals, set_color white will result in a grey
       font color, while set_color --bold white will result in a white font color.

       Not all terminal emulators support all these features. This is not a bug in set_color but a missing feature in the terminal emulator.

       set_color uses the terminfo database to look up how to change terminal colors on whatever terminal is in use. Some systems have old and
       incomplete terminfo databases, and may lack color information for terminals that support it. Download and install the latest version of
       ncurses and recompile fish against it in order to fix this issue.

Version 1.23.1							  Sun Jan 8 2012						      set_color(1)
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