NCL Website header
NCL Home > Documentation > Functions > File IO

cbinread

Reads binary files created using the C block I/O function write.

Prototype

	function cbinread (
		filename [1] : string,           
		dsizes   [*] : integer or long,  
		datatype [1] : string            
	)

	return_val [as_specified_in_dsizes] :  datatype

Arguments

filename

Name of binary file to open. May include an absolute or relative path to the file.

dsizes

An array specifying the dimension sizes of the data to be read, or the value -1 to indicate an unknown size.

As of version 6.0.0, dsizes can be of type int or long.

datatype

A string representing the type of the data being read (for example, "float", "integer").

Return value

The variable returned will have the dimension sizes specified the dsizes argument and the type specified by datatype.

Description

The cbinread function is used to read in binary data created using the C block I/O function write.

Note: As with any binary file, the "endian-ness" of the data on the file and that of the current system must agree. The "ReadByteOrder" option in the setfileoption procedure can be used to force the "endian" type in a file. This allows big-endian files to be read on a little-endian machine and vice versa. The isbigendian function can be used to determine the endian-ness of your current system.

If the dsizes array specifies a size less than the total file size, only the first n values of the file will be read in, where n is the product of the dimension sizes times the size of the specified type. If the size implied by the dimension sizes is greater than the file size, then the remaining space in the returned value is padded with the default missing value for the specified type. In both of these cases, warnings are printed. Note there is no way for NCL to determine if the type of file and the datatype argument represent the same type. If the value of -1 is used for dsizes, then the entire file is read into a single dimension variable with a dimension length equal to the number of elements in the file.

See Also

setfileoption, fbindirread, fbinrecread, cbinwrite, isbigendian

Examples

;
; Write a flat binary file called "tmp_file_x" with six elements.
;
    x = (/10.,20.,30.,40.,50.,60./)
    cbinwrite("tmp_file_x",x)
;
; Read the file back in. "y" will be an array of length 6. 
;
    y = cbinread("tmp_file_x",-1,"float")
    print(y)
;
; Read the  same file, only this time formatting it as a 2 x 3 array.
;
    z = cbinread("tmp_file_x",(/2,3/),"float")
    print(z)