CFile read

iayd

Hi, I want to read a .txt file frequently.I wrote this code;

char *pbuf = new char(file.GetLength())
file.Read( pbuf,file.GetLength());

In this way occured an error and program shut down while it is running. But when I wrote

char pbuf[100];
file.Read( pbuf,100);

this code doesn't produce an error. But I wil not know the size of the file.What can I do for that? Thanks

Dominik Reichl

Instead of

char *pbuf = new char(file.GetLength())

use

char *pbuf = new char**[file.GetLength()];**

Also, don't forget to delete []pbuf, when you've finished using it.

Too many passwords to remember? Try KeePass Password Safe!

Iain Clarke Warrior Programmer

1/

new char [file.GetLength()];

2/ You are making a buffer exactly as long as the file - and as it's char buffer, you're likely to be expecting it to be NULL terminated. Which it won't be... Your second example reads *upto* 100 chars, so will probably be less, and as that chunk of 100 bytes probably has a zero or two in it, you get away with it. Make a text file 100 bytes long, and it would likely fail too. 3/ I'd put the size into a variable, if only for debugging purposes. 4/ You could also have some naughty person save a '\0' somewhere in the file, so your string would be messed up... Especially if this program ends up in the wild. The effect could be benign: "Ok, it will look like there was less text. big deal", or critical, depending on your code. Iain.

Plz sir... CPallini CPallini abuz drugz, plz plz help urgent.

toxcct

as long as you're using MFC, why don't you use CString instead of char* ?

[VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

Rajesh R Subramanian

Use the rant icon. :-D

Nobody can give you wiser advice than yourself. - Cicero .·´¯`·->Rajesh<-·´¯`·. Codeproject.com: Visual C++ MVP

toxcct

nope, i wasn't ranting, i was just advising, on an interrogative way... :cool:

[VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

Rajesh R Subramanian

Actually yours was a good suggestion and so, could be a rant. :)

Nobody can give you wiser advice than yourself. - Cicero .·´¯`·->Rajesh<-·´¯`·. Codeproject.com: Visual C++ MVP

David Crow

iayd wrote:

char *pbuf = new char(file.GetLength()) file.Read( pbuf,file.GetLength()); In this way occured an error

What error? A missing semicolon, perhaps? Did new fail? Did GetLength() fail? Did Read() fail? Be specific.

"Love people and use things, not love things and use people." - Unknown

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne