Loops

tootypegs · #1 03-Jan-2008, 17:50

Hi im having a problem creating some loops in my program.

Basically i was trying to impliment a loop that runs until 16384 bytes have been captured. I then want to run a loop inside this one that cuts the 16384 bytes into 32 byte chunks starting at the first byte and cutting it into chunks from there. I have had a go at this but i cnt seem to get anything to work,
can anyone help me to correctly impliment this? thanks

Code:


char iobuf[32];     //hold the 32 byte chunk

f.seekg (START_OF_ROOT,std::ios::beg) ;   // Positions at start of the 16384 bytes 

 for(i= 0; i < 16348; i++)
{

while( iobuf<=sizeof(iobuf))
{
   f.read (&iobuf,sizeof (iobuf)) ;
}

}

fakepoo · #2 04-Jan-2008, 07:22

It sounds to me like you want to store your bytes into an array like:

CPP / C++ / C Code:

unsigned char data[512][32];

Then, you can have two loops like this:

CPP / C++ / C Code:

int i,j;
for(i=0;i<512;++i)
{ for(j=0;j<32;j++)
  { // read a byte into data[i][j]
  }
}

Is this the solution you were looking for or am I misunderstanding you?

tootypegs · #3 04-Jan-2008, 08:49

Yer overal i have for example 512 bytes. I need to loop through the 512 bytes starting at byte 1. I need to capture a block of 32 bytes. With that 32 bytes i need to look at the structure and do some calculations. Once im done with that 32 bytes i would then need to move to the next 32 which will be bytes 33-64 and produce the same calculations. This would have to be done until i finally example all chunks in the 512 bytes

fakepoo · #4 04-Jan-2008, 09:25

OK. How about this:

CPP / C++ / C Code:

int i,j;
char iobuff[32];
for(i=0;i<512;++i)
{ for(j=0;j<32;++j)
  { // read a byte into iobuff[j]
  }
  
  // Process iobuff[] here
}

davekw7x · #5 04-Jan-2008, 11:10

Quote:

Originally Posted by fakepoo

OK. How about this:

CPP / C++ / C Code:

for(i=0;i<512;++i)
{ for(j=0;j<32;++j)
  { // read a byte into iobuff[j]

Doesn't your code attempt to read 16384 bytes? (512*32 = 16384)

Shouldn't the outer loop limit be 16? (16*32 = 512)

Regards,

Dave

fakepoo · #6 04-Jan-2008, 12:24

Quote:

Originally Posted by davekw7x

Doesn't your code attempt to read 16384 bytes? (512*32 = 16384)

Shouldn't the outer loop limit be 16? (16*32 = 512)

Regards,

Dave

Good point. The first post says 16384 and the other one says 512. I don't know.

davekw7x · #7 04-Jan-2008, 14:11

Quote:

Originally Posted by fakepoo

Good point. The first post says 16384 and the other one says 512. I don't know.

Upon reflection, I am thinking your code is in keeping with the assignment. Sorry to muddy the waters.

Regards,

Dave

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