size_limits.c File Reference

Demonstrates file size and dimension limits for NetCDF classic formats. More...

#include <stdio.h>
#include <stdlib.h>
#include <netcdf.h>
#include <sys/stat.h>

Macros
#define	ERRCODE   2
#define	ERR(e)   {printf("Error: %s\n", nc_strerror(e)); exit(ERRCODE);}
#define	CLASSIC_DIM   5000 /* ~20KB for float data */
#define	OFFSET_DIM   5000 /* ~20KB for float data */
#define	DATA_DIM   5000 /* ~20KB for float data */
#define	TEST_MODE   "SMALL"

Functions
long	get_file_size (const char *filename)
void	print_format_limits (void)
void	test_format (const char *filename, int format_flag, const char *format_name, size_t dim_size)
int	main ()

Detailed Description

Demonstrates file size and dimension limits for NetCDF classic formats.

This example explores the size limitations of the three classic NetCDF formats (CDF-1, CDF-2, CDF-5) by creating test files and explaining theoretical limits. Understanding these limits is essential for choosing the appropriate format for large datasets.

The program runs in small test mode (suitable for CI) by default, creating modest-sized test files and displaying theoretical limits. This helps users understand when they need to upgrade from CDF-1 to CDF-2 or CDF-5 for larger datasets.

Learning Objectives:

• Understand file size limits for each classic NetCDF format
• Learn when format upgrades are necessary (2GB → 4GB → unlimited)
• Calculate theoretical maximum dimensions for different data types
• Recognize format-related error messages
• Make informed decisions about format selection for large datasets

Key Concepts:

• File Size Limit: Maximum total file size (header + data)
• Variable Size Limit: Maximum size of a single variable
• Dimension Limit: Maximum dimension size based on variable limits
• Format Upgrade Path: CDF-1 → CDF-2 → CDF-5 for increasing size needs
• Practical Limits: Real-world constraints vs theoretical maximums

Format Limits Summary:

• CDF-1: 2GB file limit, 2GB variable limit (NetCDF 3.0+)
• CDF-2: Unlimited file, 4GB variable limit (NetCDF 3.6.0+)
• CDF-5: Unlimited file and variable sizes (NetCDF 4.4.0+)

Prerequisites:

• format_variants.c - Understanding format types
• simple_2D.c - Basic dimension and variable concepts

Related Examples:

• f_size_limits.f90 - Fortran equivalent
• format_variants.c - Format comparison
• simple_nc4.c - NetCDF-4 format (different size limits)

Compilation:

gcc -o size_limits size_limits.c -lnetcdf

Usage:

./size_limits

Expected Output:

• Creates small test files in each format
• Displays theoretical size limits
• Shows file sizes and dimension calculations
• Provides guidance on format selection

Author

Edward Hartnett, Intelligent Data Design, Inc.

Date

2026

Macro Definition Documentation

CLASSIC_DIM

#define CLASSIC_DIM   5000 /* ~20KB for float data */

DATA_DIM

#define DATA_DIM   5000 /* ~20KB for float data */

ERR

#define ERR

(

e

)

{printf("Error: %s\n", nc_strerror(e)); exit(ERRCODE);}

ERRCODE

#define ERRCODE   2

OFFSET_DIM

#define OFFSET_DIM   5000 /* ~20KB for float data */

TEST_MODE

#define TEST_MODE   "SMALL"

Function Documentation

get_file_size()

long get_file_size

(

const char *

filename

)

main()

int main

(

)

print_format_limits()

void print_format_limits

(

void

)

test_format()

void test_format	(	const char *	filename,
		int	format_flag,
		const char *	format_name,
		size_t	dim_size
	)