|GNU Octave Manual Version 3|
by John W. Eaton, David Bateman, Søren Hauberg
Paperback (6"x9"), 568 pages
RRP £24.95 ($39.95)
14.2.4 Formatted Output
This section describes how to call
printf and related functions.
The following functions are available for formatted output. They are modelled after the C language functions of the same name, but they interpret the format template differently in order to improve the performance of printing vector and matrix values.
- Built-in Function: printf (template, ...)
- Print optional arguments under the control of the template string
template to the stream
stdoutand return the number of characters printed.
See also fprintf, sprintf, scanf
- Built-in Function: fprintf (fid, template, ...)
- This function is just like
printf, except that the output is written to the stream fid instead of
See also printf, sprintf, fread, fscanf, fopen, fclose
- Built-in Function: sprintf (template, ...)
- This is like
printf, except that the output is returned as a string. Unlike the C library function, which requires you to provide a suitably sized string as an argument, Octave's
sprintffunction returns the string, automatically sized to hold all of the items converted.
See also printf, fprintf, sscanf
printf function can be used to print any number of arguments.
The template string argument you supply in a call provides
information not only about the number of additional arguments, but also
about their types and what style should be used for printing them.
Ordinary characters in the template string are simply written to the output stream as-is, while conversion specifications introduced by a ‘%’ character in the template cause subsequent arguments to be formatted and written to the output stream. For example,
pct = 37; filename = "foo.txt"; printf ("Processed %d%% of `%s'.\nPlease be patient.\n", pct, filename);
produces output like
Processed 37% of `foo.txt'. Please be patient.
This example shows the use of the ‘%d’ conversion to specify that a scalar argument should be printed in decimal notation, the ‘%s’ conversion to specify printing of a string argument, and the ‘%%’ conversion to print a literal ‘%’ character.
There are also conversions for printing an integer argument as an unsigned value in octal, decimal, or hexadecimal radix (‘%o’, ‘%u’, or ‘%x’, respectively); or as a character value (‘%c’).
Floating-point numbers can be printed in normal, fixed-point notation using the ‘%f’ conversion or in exponential notation using the ‘%e’ conversion. The ‘%g’ conversion uses either ‘%e’ or ‘%f’ format, depending on what is more appropriate for the magnitude of the particular number.
You can control formatting more precisely by writing modifiers between the ‘%’ and the character that indicates which conversion to apply. These slightly alter the ordinary behavior of the conversion. For example, most conversion specifications permit you to specify a minimum field width and a flag indicating whether you want the result left- or right-justified within the field.
The specific flags and modifiers that are permitted and their interpretation vary depending on the particular conversion. They're all described in more detail in the following sections.
|ISBN 095461206X||GNU Octave Manual Version 3||See the print edition|