The warning function also allows you to control which warnings
are actually printed to the screen. If the warning function
is called with a string argument that is either "on" or "off"
all warnings will be enabled or disabled.
It is also possible to enable and disable individual warnings through their string identifications. The following code will issue a warning
warning ("non-negative-variable",
"'a' must be non-negative. Setting 'a' to zero.");
while the following won't issue a warning
warning ("off", "non-negative-variable");
warning ("non-negative-variable",
"'a' must be non-negative. Setting 'a' to zero.");
The functions distributed with Octave can issue one of the following warnings.
Octave:array-to-scalarOctave:array-to-scalar warning is enabled, Octave will
warn when an implicit conversion from an array to a scalar value is
attempted. By default, the Octave:array-to-scalar warning is
disabled.
Octave:array-to-vectorOctave:array-to-vector warning is enabled, Octave will
warn when an implicit conversion from an array to a vector value is
attempted. By default, the Octave:array-to-vector warning is
disabled.
Octave:assign-as-truth-valueOctave:assign-as-truth-value warning is
enabled, a warning is issued for statements like
if (s = t)
...
since such statements are not common, and it is likely that the intent was to write
if (s == t)
...
instead.
There are times when it is useful to write code that contains
assignments within the condition of a while or if
statement. For example, statements like
while (c = getc())
...
are common in C programming.
It is possible to avoid all warnings about such statements by
disabling the Octave:assign-as-truth-value warning,
but that may also let real errors like
if (x = 1) # intended to test (x == 1)!
...
slip by.
In such cases, it is possible suppress errors for specific statements by writing them with an extra set of parentheses. For example, writing the previous example as
while ((c = getc()))
...
will prevent the warning from being printed for this statement, while allowing Octave to warn about other assignments used in conditional contexts.
By default, the Octave:assign-as-truth-value warning is enabled.
Octave:associativity-changeOctave:associativity-change warning is
enabled, Octave will warn about possible changes in the meaning of
some code due to changes in associativity for some operators.
Associativity changes have typically been made for matlab
compatibility. By default, the Octave:associativity-change
warning is enabled.
Octave:divide-by-zeroOctave:divide-by-zero warning is enabled, a
warning is issued when Octave encounters a division by zero. By
default, the Octave:divide-by-zero warning is enabled.
Octave:empty-list-elementsOctave:empty-list-elements warning is enabled, a
warning is issued when an empty matrix is found in a matrix list.
For example,
a = [1, [], 3, [], 5]
By default, the Octave:empty-list-elements warning is enabled.
Octave:fortran-indexingOctave:fortran-indexing warning is enabled, a warning is
printed for expressions which select elements of a two-dimensional matrix
using a single index. By default, the Octave:fortran-indexing
warning is disabled.
Octave:function-name-clashOctave:function-name-clash warning is enabled, a
warning is issued when Octave finds that the name of a function
defined in a function file differs from the name of the file. (If
the names disagree, the name declared inside the file is ignored.)
By default, the Octave:function-name-clash warning is enabled.
Octave:future-time-stampOctave:future-time-stamp warning is enabled, Octave
will print a warning if it finds a function file with a time stamp
that is in the future. By default, the
Octave:future-time-stamp warning is enabled.
Octave:imag-to-realOctave:imag-to-real warning is enabled, a warning is
printed for implicit conversions of complex numbers to real numbers.
By default, the Octave:imag-to-real warning is disabled.
Octave:matlab-incompatibleOctave:missing-semicolonOctave:missing-semicolon warning is enabled, Octave
will warn when statements in function definitions don't end in
semicolons. By default the Octave:missing-semicolon warning
is disabled.
Octave:neg-dim-as-zeroOctave:neg-dim-as-zero warning is enabled, print a warning
for expressions like
eye (-1)
By default, the Octave:neg-dim-as-zero warning is disabled.
Octave:num-to-strOctave:num-to-str warning is enable, a warning is
printed for implicit conversions of numbers to their ASCII character
equivalents when strings are constructed using a mixture of strings and
numbers in matrix notation. For example,
[ "f", 111, 111 ]
=> "foo"
elicits a warning if the Octave:num-to-str warning is
enabled. By default, the Octave:num-to-str warning is enabled.
Octave:precedence-changeOctave:precedence-change warning is enabled, Octave
will warn about possible changes in the meaning of some code due to
changes in precedence for some operators. Precedence changes have
typically been made for matlab compatibility. By default, the
Octave:precedence-change warning is enabled.
Octave:reload-forces-clearOctave:reload-forces-clear warning is enabled, Octave will
warn you when this happens, and print a list of the additional
functions that it is forced to clear. By default, the
Octave:reload-forces-clear warning is enabled.
Octave:resize-on-range-errorOctave:resize-on-range-error warning is enabled, print a
warning when a matrix is resized by an indexed assignment with
indices outside the current bounds. By default, the
Octave:resize-on-range-error warning is disabled.
Octave:separator-insertOctave:single-quote-stringOctave:str-to-numOctave:str-to-num warning is enabled, a warning is printed
for implicit conversions of strings to their numeric ASCII equivalents.
For example,
"abc" + 0
=> 97 98 99
elicits a warning if the Octave:str-to-num warning is enabled.
By default, the Octave:str-to-num warning is disabled.
Octave:string-concatOctave:string-concat warning is enabled, print a
warning when concatenating a mixture of double and single quoted strings.
By default, the Octave:string-concat warning is disabled.
Octave:undefined-return-valuesOctave:undefined-return-values warning is disabled,
print a warning if a function does not define all the values in
the return list which are expected. By default, the
Octave:undefined-return-values warning is enabled.
Octave:variable-switch-labelOctave:variable-switch-label warning is enabled, Octave
will print a warning if a switch label is not a constant or constant
expression. By default, the Octave:variable-switch-label
warning is disabled.