|MATLAB Function Reference|
Read formatted data from file
A = fscanf(fid,format)
reads all the data from the file specified by
fid, converts it according to the specified
format string, and returns it in matrix
fid is an integer file identifier obtained from
format is a string specifying the format of the data to be read. See "Remarks" for details.
[A,count] = fscanf(fid,format,size)
reads the amount of data specified by
size, converts it according to the specified
format string, and returns it along with a
count of elements successfully read.
size is an argument that determines how much data is read. Valid options are:
n elements into a column vector.
Read to the end of the file, resulting in a column vector containing the same number of elements as are in the file.
Read enough elements to fill an
n matrix, filling the matrix in column order.
n can be
Inf, but not
fscanf differs from its C language namesakes
() in an important respect -- it is vectorized in order to return a matrix argument. The
format string is cycled through the file until an end-of-file is reached or the amount of data specified by
size is read in.
When MATLAB reads a specified file, it attempts to match the data in the file to the format string. If a match occurs, the data is written into the matrix in column order. If a partial match occurs, only the matching data is written to the matrix, and the read operation stops.
format string consists of ordinary characters and/or conversion specifications. Conversion specifications indicate the type of data to be matched and involve the character
%, optional width fields, and conversion characters, organized as shown below:
Add one or more of these characters between the
% and the conversion character:
|An asterisk (
||Skip over the matched value. If
|A digit string
||Maximum field width. For example,
||The size of the receiving object; for example,
Valid conversion characters are:
||Sequence of characters; number specified by field width
||Signed octal integer
||A series of non-white-space characters
||Signed decimal integer
||Signed hexadecimal integer
||Sequence of characters (scanlist)
%s is used, an element read may use several MATLAB matrix elements, each holding one character. Use
%c to read space characters or
%s to skip all white space.
Mixing character and numeric conversion specifications cause the resulting matrix to be numeric and any characters read to appear as their ASCII values, one character per MATLAB matrix element.
For more information about format strings, refer to the
fscanf() routines in a C language reference manual.
The example in
fprintf generates an ASCII text file called
exp.txt that looks like:
Read this ASCII file back into a two-column MATLAB matrix: