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Reading a text file......

hooshdar3 (257)
Hi.
What is wrong with me reading the text file?
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int main(){
...........
    int fh = _open("g://PA2//10.txt" , fh);
    fh=_read(fh,a,70000);
...............
    for(int k=0;k<20;++k)
       cout << a[k] <<' ';

    cout<< endl;  
.................
return 0;
}
Last edited on
Thomas1965 (4571)
You need to specify in what mode you want to open the file.
You also need to check if the file could be opened.
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int fh = _open("g://PA2//10.txt" , _O_RDONLY);
if (fh <> -1)
  // read your file here.


See here for documentation and example:
https://msdn.microsoft.com/en-us/library/z0kc8e3z%28v=vs.100%29.aspx
hooshdar3 (257)
Thanks.But the problem is this:

I need to print my file this way:
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    for(int k=-4;k<100;++k)
       cout << a[k] <<' ';

    cout<< endl;


A problem I have never faced in my whole life!



Last edited on
Thomas1965 (4571)
I need to print my file this way:
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for(int k=-4;k<100;++k)
  cout << a[k] <<' ';


Why?

I guess a is a kind of array and the first element is a[0].
If you try sth. like cout << a[-4] it will most likely crash.
hooshdar3 (257)
I could not figure out myself

That worked for an ad-hoc content and not for another content.
Last edited on
Thomas1965 (4571)
What is the problem ?
hooshdar3 (257)
After reading, I'd have strange characters in my file.
Then when I convert them to numbers, I get unexpected results.
Thomas1965 (4571)
Can you post part of the file?
jlb (4973)
How was a declared?

Are you sure you've actually read the number of characters you're trying to print?

Wouldn't it be better to use the value returned from your _read() call to control your loop?

hooshdar3 (257)
The file:
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------------------------------------------------
Def. of a:
char a[700000];
jlb (4973)
Why are you trying to read a series of numbers as a series characters?

And why are you trying to use the low level function _open() instead of the higher level functions? If you're writing a C function fopen() or in C++ using the file streams.
hooshdar3 (257)
OK, I was making a stupid mistake in making fh get the value of _read(fh, ...)
Interesting.................I was taught that the RHS of the assignment gets evaluated first.
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