fwrite

Syntax

R = fwrite(fileID, data, precision, skip)

Inputs

fileID

File ID returned from earlier call to fopen().

Type: double | integer

data

Matrix of values to be written.

Dimension: vector | matrix

precision

String specifying the type of data to write.

Type: char | string

Valid precision types:

'char' or 'char*1' or 'schar' or 'signed char' for a single character.
'uchar' or 'unsigned char' for unsigned character.
'ulong' or 'unsigned long' for platform dependent unsigned long integer.
'uint' or'unsigned int' for platform dependent unsigned integer.
'ushort' or 'unsigned short' for platform dependent unsigned short integer.
'long' for platform dependent long integer.
'int' for platform dependent integer.
'short for platform dependent short integer.
'uint64' for 64 bit unsigned integer.
'uint32' for 32 bit unsigned integer.
'uint16' for 16 bit unsigned integer.
'uint8' for 8 bit unsigned integer.
'int8' or 'integer*1' for 8 bit signed integer.
'int16' or 'integer*2' for 16 bit signed integer.
'int32' or 'integer*4' for 32 bit signed integer.
'int64' or 'integer*8' for 64 bit signed integer.
'float' for platform dependent single precision floating point number.
'double' or 'float64' or 'real*8' for 64 bit floating point number.
'single' or 'float32' or 'real*4' for 32 bit floating point number.

skip (optional)

Argument specifying the number of bytes to skip after writing each value. If unspecified, the value is 0.

Type: double | integer

Outputs

R: Number of values written to the file.; Type: double | integer

Example

Read example using fwrite and fread functions:

% open file using 'w+'
fileID = fopen('testfile', 'w+')
% create a matrix
M = [ 1923.71288  4023.03575  9768.82832  9195.83701  104.13143  4261.35201   ];
% write matrix to file
fwrite_result = fwrite(fileID, M, 'double')
fflush_result = fflush(fileID)
printf('\n')
% return as much as possible in a column vector
frewind_result = frewind(fileID);
R1 = fread(fileID, inf, 'double');
printf('Matrix dimensions: columns %2d  rows %2d\n', size(R1)(2), size(R1)(1));

% return 2 values in a column vector
frewind_result = frewind(fileID);
R2 = fread(fileID, 2, 'double');
printf('Matrix dimensions: columns %2d  rows %2d\n', size(R2)(2), size(R2)(1));

% return as much as possible in 2 rows
frewind_result = frewind(fileID);
R3 = fread(fileID, [2, inf], 'double');
printf('Matrix dimensions: columns %2d  rows %2d\n', size(R3)(2), size(R3)(1));

% return 2 entries in 1 row
frewind_result = frewind(fileID);
R4 = fread(fileID, [1, 2], 'double');
printf('Matrix dimensions: columns %2d  rows %2d\n', size(R4)(2), size(R4)(1));

fclose_result = fclose(fileID)

fileID = 5
fwrite_result = 6
fflush_result = 0
 
Matrix dimensions: columns  1  rows  6
Matrix dimensions: columns  1  rows  2
Matrix dimensions: columns  3  rows  2
Matrix dimensions: columns  2  rows  1
fclose_result = 0