How to access the value that a pointer is pointing to
How to access the value that a pointer is pointing to
- Subject: How to access the value that a pointer is pointing to
- From: Phil Faber <email@hidden>
- Date: Sat, 29 Apr 2006 15:09:23 +0100
The following code successfully copies a file, byte-by-byte. It uses
fread(&oneByte,1,1,fp1) to read in a byte and fwrite(&oneByte,
1,1,fp2) to write that byte back to disc.
I want to be able to analyse the byte before it writes back to disc
but can't see how to see its value. oneByte is a pointer to the
value - not the value itself. I need to do something like:
oneByteASCII=(value of byte at pointer 'oneByte')
How can I achieve this? I know this must be a newbie question but I
have a good excuse ... I AM a relative newbie!
Any help would be appreciated. It would be really great if someone
could convert:
oneByteASCII=(value of byte at pointer 'oneByte')
..to some legal line of code that actually achieves the goal!
Thanks.
Phil
// Used to store currently read byte
int oneByte, oneByteASCII;
// Provide dialogue box to select file
NSOpenPanel *panel = [NSOpenPanel openPanel];
int result = [panel runModalForDirectory:nil file:nil types:nil];
// Put file name into inputFile
NSString *inputFile = [panel filename];
NSMutableString *outputFile;
outputFile = [NSMutableString stringWithFormat: @"%@-A", inputFile];
// Prepare file pointer to open selected file
FILE *fp1;
// Prepare file pointer to write to output file
FILE *fp2;
// Set file pointer to selected file
fp1 = fopen([inputFile UTF8String],"rb");
fp2 = fopen([outputFile UTF8String],"wb");
// Read a byte
fread(&oneByte,1,1,fp1);
while(feof(fp1)==0)
{
// Write the byte
fwrite(&oneByte,1,1,fp2);
// ** This is not legal code but shows what I'm trying to achieve
here! **
oneByteASCII=(value of byte at pointer 'oneByte');
// Read next byte
fread(&oneByte,1,1,fp1);
}
// Close files
fclose(fp1);
fclose(fp2);
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