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Determine if a string is numeric: Difference between revisions
→{{header|Haskell}}: ++ gnu octave
(→{{header|Haskell}}: ++ gnu octave) |
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s" beef" is-numeric \ beef as integer = BEEF
s" &1234" is-numeric \ &1234 as integer = 4D2 ( decimal literal )
=={{header|GNU Octave}}==
The builtin function <tt>isnumeric</tt> return true (1) if the argument is a data of type ''number''; the provided function <tt>isnum</tt> works the same for numeric datatype, while if another type is passed as argument, it tries to convert it to a number; if the conversion fails, it means it is not a string representing a number.
<lang octave>function r = isnum(a)
if ( isnumeric(a) )
r = 1;
else
o = str2num(a);
r = !isempty(o);
endif
endfunction
% tests
disp(isnum(123)) % 1
disp(isnum("123")) % 1
disp(isnum("foo123")) % 0
disp(isnum("123bar")) % 0
disp(isnum("3.1415")) % 1</lang>
=={{header|Haskell}}==
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