ReadFile() Problem

[goldenrose9]

Content of a.txt

Hello How are you
Welcome

Function used to read the File

void ReadBytes(__inout BYTE *pBuffer, DWORD dwSize)
{
//BYTE *pBuffer = new BYTE[dwSize];
DWORD dwRead;

if (hFile != INVALID\_HANDLE\_VALUE)		
ReadFile(hFile,pBuffer,dwSize,&dwRead,NULL);	

}

int main()
{
myFile mObj;
BYTE* hSrc = new BYTE[26];
mObj.ReadBytes(hSrc,26);
std::cout<

The output of the above function gives.

Hello How are you
Welcomeýýýý««««««««îþ

Why this extra characters at the end? please help:confused::confused:

Some Day I Will Prove MySelf :: GOLD

modified on Tuesday, February 1, 2011 12:44 AM

[David Crow]

goldenrose9 wrote:

Why this extra characters at the end?

Because cout will output characters until it reaches a \0.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

[goldenrose9]

i had checked this with file mapping. In file mapping when i use cout to display the hSrc value it gives the correct output. then why it is displaying extra characters when i am using ReadFile method. Is there any problem in my code. please help:confused:

Some Day I Will Prove MySelf :: GOLD

[David Crow]

goldenrose9 wrote:

...then why it is displaying extra characters when i am using ReadFile method.

It has nothing to do with ReadFile().

goldenrose9 wrote:

Is there any problem in my code.

Yes, hSrc is not terminated properly.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

[Cedric Moonen]

You forgot to terminate the buffer with the null-termination character:

int main()
{
myFile mObj;
BYTE* hSrc = new BYTE[27];
mObj.ReadBytes(hSrc,26);
hSrc[26] = '\0';
std::cout<
Cédric Moonen
Software developer
Charting control [v3.0]
OpenGL game tutorial in C++

[goldenrose9]

then how to solve this.

Some Day I Will Prove MySelf :: GOLD

[David Crow]

See here.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"Man who follows car will be exhausted." - Confucius

[goldenrose9]

thanx :) :thumbsup:

Some Day I Will Prove MySelf :: GOLD

[goldenrose9]

Cedric Moonen wrote:

BYTE* hSrc = new BYTE[27];

here you have initialized the byte array with +1 of the required value that is 26 and null terminated the byte array at 26. A small doubt. do i have to allocated the byte array +1

Some Day I Will Prove MySelf :: GOLD

[Cedric Moonen]

Yes, you have to take the termination character into account (it still counts as one char and should be allocated too). Remember that if I allocate an array of 27 characters, the last one is the character at index 26 (since the array is zero-based).

Cédric Moonen Software developer
Charting control [v3.0] OpenGL game tutorial in C++

[goldenrose9]

:) got it. sir, now the program is working fine. but when i pass a bmp or exe file to this function only few bytes from the starting is read into the buffer. Zip Archive

PK

EXE

MZ

BMP File

BM:

am i missing something again.please help..

Some Day I Will Prove MySelf :: GOLD

[Cedric Moonen]

Are you trying to print those files to the console ? :~ This won't work, since they contain binary information which can perfectly be the character with ASCII code 0 (which will be considered as the end of the string). What are you trying to do here ?

Cédric Moonen Software developer
Charting control [v3.0] OpenGL game tutorial in C++