February 26th, 2017, 09:33 PM
how to write binary file without deleting its previous contents
I am writing a binary file like this:
Now how can i again write given binary file obj_pattern.bin with some new values of ad[i] in another program. For example in first program i put ad values in the file as 1,2 now how can i again write that same file without deleting the previous saved values 1 and 2?
const int sized = 300000000ULL;
ad[i] = some value;
pFile = fopen("obj_pattern.bin", "wb");
fwrite(ad, 1, sized*sizeof(int), pFile);
Last edited by dinesh999lama; February 26th, 2017 at 09:36 PM.
February 27th, 2017, 02:25 AM
Re: how to write binary file without deleting its previous contents
Mode "wb" will delete any existing contents. If you open the file as mode "ab", this will append the data to the existing contents. There is also mode "a+b" which will allow reading from the file at a specified position but writing to the end of the file. If you use mode "r+b" then you can position the file pointer to the end of the file before you write but the file must exist.
Last edited by 2kaud; February 27th, 2017 at 02:32 AM.
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C, C++ Compiler: Microsoft VS2017
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