Determine if a string is numeric: Difference between revisions

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To check whether a string is a number, a fraction or an integer, use the patterns <code>#</code>, <code>/</code> and <code>~/#</code> ("not a fraction and yet a number"). In the pattern matching examples below (which can be typed in at the Bracmat prompt) <code>F</code> denotes 'failure' and <code>S</code> denotes 'success'.
To check whether a string is a number, a fraction or an integer, use the patterns <code>#</code>, <code>/</code> and <code>~/#</code> ("not a fraction and yet a number"). In the pattern matching examples below (which can be typed in at the Bracmat prompt) <code>F</code> denotes 'failure' and <code>S</code> denotes 'success'.


<lang>43257349578692:/
<lang bracmat>43257349578692:/
F
F


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S</lang>
S</lang>
Bracmat doesn't do floating point computations (historical reason: the Acorn Risc Machine a.k.a. ARM processor in the Archimedes computer did not have an FPU), but the pattern <code>~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#)</code> recognises string representations of floating point numbers.
Bracmat doesn't do floating point computations (historical reason: the Acorn Risc Machine a.k.a. ARM processor in the Archimedes computer did not have an FPU), but the pattern <code>~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#)</code> recognises string representations of floating point numbers.
<lang>@("1.000-4E-10":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
<lang bracmat>@("1.000-4E-10":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
F
F


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To do computations with such "floating point strings" you would have to convert such strings to fractional representations first.
To do computations with such "floating point strings" you would have to convert such strings to fractional representations first.
<lang>(float2fraction=
<lang bracmat>(float2fraction=
integerPart decimalPart d1 dn exp sign
integerPart decimalPart d1 dn exp sign
. @( !arg
. @( !arg
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</lang>
</lang>
Output:
Output:
<lang>6/5
<pre>6/5
51/50
51/50
101/100
101/100
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-1001/10000
-1001/10000
-1/10
-1/10
0</lang>
0</pre>

=={{header|C}}==
=={{header|C}}==
Returns true (non-zero) if character-string parameter represents a signed or unsigned floating-point number. Otherwise returns false (zero).
Returns true (non-zero) if character-string parameter represents a signed or unsigned floating-point number. Otherwise returns false (zero).
Retrieved from "https://rosettacode.org/wiki/Determine_if_a_string_is_numeric"