Determine if a string is numeric: Difference between revisions
Content added Content deleted
(→{{header|MATLAB}}: mark incorrect) |
(Added Bracmat example) |
||
Line 154:
'12+3' is NOT a number
'end' is NOT a number</pre>
=={{header|Bracmat}}==
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:/
F
260780243875083/35587980:/
S
247/30:~/#
F
80000000000:~/#
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.
<lang>@("1.000-4E-10":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
F
@("1.0004E-54328":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S
@("-464641.0004E-54328":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S
@("1/2.0004E-10":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
F
@("1357E-10":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S
@("1357e0":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S
@("13579":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S
@("1.246":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S
@("0.0":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S
@("0.0000":~/# (|"." (|? 0|`) (|~/#:>0)) (|(E|e) ~/#))
S</lang>
To do computations with such "floating point strings" you would have to convert such strings to fractional representations first.
<lang>(float2fraction=
integerPart decimalPart d1 dn exp sign
. @( !arg
: ~/#?integerPart
( &0:?decimalPart:?d1:?dn
| "."
[?d1
(|? 0|`)
( &0:?decimalPart
| ~/#?decimalPart:>0
)
[?dn
)
( &0:?exp
| (E|e) ~/#?exp
)
)
& ( !integerPart*(-1:?sign):>0:?integerPart
| 1:?sign
)
& !sign*(!integerPart+!decimalPart*10^(!d1+-1*!dn))*10^!exp
);
( out$float2fraction$"1.2"
& out$float2fraction$"1.02"
& out$float2fraction$"1.01"
& out$float2fraction$"10.01"
& out$float2fraction$"10.01e10"
& out$float2fraction$"10.01e1"
& out$float2fraction$"10.01e2"
& out$float2fraction$"10.01e-2"
& out$float2fraction$"-10.01e-2"
& out$float2fraction$"-10e-2"
& out$float2fraction$"0.000"
);
</lang>
Output:
<lang>6/5
51/50
101/100
1001/100
100100000000
1001/10
1001
1001/10000
-1001/10000
-1/10
0</lang>
=={{header|C}}==
Returns true (non-zero) if character-string parameter represents a signed or unsigned floating-point number. Otherwise returns false (zero).
| |||