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Full Discussion: Unclear pointer and array
Top Forums Programming Unclear pointer and array Post 302884194 by Don Cragun on Saturday 18th of January 2014 09:12:53 AM
Old 01-18-2014
It wastes exactly the same amount of space your code wasted. My changes to your code just made changes to keep you from overwriting data following the space pointed to by text if your input string is longer than the space you allocated for your buffer.

Are you going to keep 100 millions of lines of data in memory at once, or are you going to process a line at a time? If you are processing a line at a time, wasting something less than 100 bytes is absolutely nothing to worry about.

If you're going to try to malloc() 100 million buffers for your output substrings, you need to reconsider lots of issues as you design code to deal with that much data. (Note that you're talking about 800,000,000 bytes just to hold the pointers to your buffers!) Obviously, you could allocate space for your output buffer in your substring() function based on the length of the string it is actually going to store into that buffer.
This User Gave Thanks to Don Cragun For This Post:
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LEARN ABOUT SUNOS

tiffwritebuffersetup

TIFFbuffer(3tiff)					 Introduction to Library Functions					 TIFFbuffer(3tiff)

NAME

       TIFFbuffer, TIFFReadBufferSetup, TIFFWriteBufferSetup - I/O buffering control routines

SYNOPSIS

       #include <tiffio.h>
       int TIFFReadBufferSetup(TIFF*, tdata_t buffer, tsize_t size);
       int TIFFWriteBufferSetup(TIFF*, tdata_t buffer, tsize_t size);

DESCRIPTION

       The  following routines are provided for client-control of the I/O buffers used by the library. Applications need never use these routines.
       The routines are provided only for "intelligent clients" that wish to optimize memory usage and/or eliminate potential copy operations that
       can occur when working with images that have data stored without compression.

EXTENDED DESCRIPTION

       TIFFReadBufferSetup  sets  up  the data buffer used to read raw (encoded) data from a file. If the specified pointer is NULL (zero), then a
       buffer of the appropriate size is allocated. Otherwise, the caller must guarantee that the buffer is large enough to  hold  any	individual
       strip of raw data. TIFFReadBufferSetup returns a non-zero value if the setup was successful.

       TIFFWriteBufferSetup  sets  up the data buffer used to write raw (encoded) data to a file. If the specified size is -1 then the buffer size
       is selected to hold a complete tile or strip, or at least 8 kilobytes, whichever is greater. If the specified buffer is NULL (zero), then a
       buffer of the appropriate size is dynamically allocated. TIFFWriteBufferSetup returns a non-zero value if the setup was successful.

   Diagnostics
       %s: No space for data buffer at scanline %ld.

	   TIFFReadBufferSetup was unable to dynamically allocate space for a data buffer.

       %s: No space for output buffer.

	   TIFFWriteBufferSetup was unable to dynamically allocate space for a data buffer.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWTiff			   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |External			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       libtiff(3)

NOTES

       This man page was originally written by Sam Leffler. Updated by Breda McColgan, Sun Microsystems Inc., 2004.

SunOS 5.10							    01 Apr 2004 						 TIFFbuffer(3tiff)
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