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How can you write X character in a X position in a file without erasing the rest?
Like if you have a file
"Name:Tom and Jerry\n"
and you want
"Name: George and Jerry\n"
how it should be done effectively?
I believe fputc(), fwrite() overwrite existing data in the file so they are not useful. Like they would do:
"Name: GeorgedJerry\n"
You can't. You need to move the data (push it, so to speak), to make room for more data.
Code:"Name:Tom and Jerry\n"
"Name:Tom and Jerry\n"
"Name:George and Jerry\n"
Is there a function to do that for you? Like an fwrite() that pushes data...
No, you'll have to do it manually.
In this example, read "and Jerry\n" (everything after the "Name:Tom " part).
Calculate the difference of length "Name:George " - "Name:Tom " (which is 3 in this case).
Seek to "Name:Tom " + offset you calculated. Write the data you read.
The result should be something like:
"Name:Tom andand Jerry\n"
Now you'll have enough space to write overwrite "Name:Tom and" with "Name:George "
Or, alternatively, write a new file with the new information (all of it, even the stuff that didn't change), and then later, copy it to the old filename.
Thanx. I have done it as tabstop said, I just expected for their to be already a function. Usually I first create a function to do my job and search later if it was already there :P
Ah well, no. Unfortunately, there is no such function at OS level, either, so it's not like it's a failing in the C library (it was meant to be low level).