Determine if a string is numeric: Difference between revisions
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You entered a number.</pre>
NB: While "99, rue de Rivoli" contains a number it is not a number entirely. The Val(v$) in this case would have stopped after it converted the "99" portion of the input, which when converted back to a string and compared to the original input would not result in an equality. 9E4 the program reads as an exponential value.
==={{header|SmallBASIC}}===
y = isnumber(s) returns true if s is a number or can be converted to a number.
<syntaxhighlight lang="qbasic">
a = 1.2345
b = "abc"
c = "-1.2345"
print isnumber(a)
print isnumber(b)
print isnumber(c)
</syntaxhighlight>
{{out}}
<pre>
1
0
1
</pre>
=={{header|Batch File}}==
Line 2,001 ⟶ 2,020:
→ YES
</syntaxhighlight>
=={{header|Ed}}==
<syntaxhighlight lang="sed">
H
g/^([-+]?[0-9]*)(\.[0-9]+([eE][+-]?[0-9]+)?)?$/s//\1\2 is numeric/
v/numeric/s/.*/& is not numeric/
,p
Q
</syntaxhighlight>
{{out}}
<pre>$ cat string-numeric.ed | ed -GlEs string-numeric.input
Newline appended
56233 is numeric
-315 is numeric
1.36 is numeric
-5.126 is numeric
3.7E-05 is numeric
1.23BC is not numeric
5.6.3 is not numeric</pre>
=={{header|Elixir}}==
Line 2,023 ⟶ 2,064:
(defun string-valid-number-p (str)
"Test if STR is a numeric string.
Eliminate strings with commas in them because
not contain commas. Then check if remaining strings would be
valid ELisp numbers if the quotation marks were removed."
Line 3,776 ⟶ 3,817:
=={{header|Pascal}}==
See [[#Delphi|Delphi]] or [[#Free Pascal|Free Pascal]].
=={{header|PascalABC.NET}}==
<syntaxhighlight lang="pascal">
function IsNumeric(s: string): boolean;
begin
var i: integer;
Result := integer.TryParse(s,i)
end;
begin
var s := '123';
if IsNumeric(s) then
Print('string is numeric')
end.
</syntaxhighlight>
=={{header|PeopleCode}}==
Line 4,540 ⟶ 4,597:
=={{header|Rust}}==
<syntaxhighlight lang="rust">
// This function is not limited to just numeric types but rather anything that implements the FromStr trait.
fn parsable<T: FromStr>(s: &str) -> bool {
s.parse::<T>().is_ok()
}
</syntaxhighlight>
Sample code:
<syntaxhighlight lang="rust">
use std::str::FromStr;
fn parsable<T: FromStr>(s: &str) -> bool {
s.parse::<T>().is_ok()
}
fn main() {
let test_cases = [
"142857",
"3.14",
"not of this earth!"
];
let types: &[(&str, fn(&str) -> bool)] = &[
("i32", parsable::<i32> as fn(&str) -> bool),
("i64", parsable::<i32> as fn(&str) -> bool),
("i128", parsable::<i32> as fn(&str) -> bool),
("f64", parsable::<f64> as fn(&str) -> bool),
];
println!("");
for &case in &test_cases {
for &(type_name, parse_fn) in types {
println!(
"'{}' {} be parsed as {}",
case,
if parse_fn(case) { "can" } else { "_cannot_" },
type_name
);
}
println!("");
}
}
</syntaxhighlight>
{{out}}
<pre>
'142857' can be parsed as i32
'142857' can be parsed as i64
'142857' can be parsed as i128
'142857' can be parsed as f64
'3.14' _cannot_ be parsed as i32
'3.14' _cannot_ be parsed as i64
'3.14' _cannot_ be parsed as i128
'3.14' can be parsed as f64
'not of this earth!' _cannot_ be parsed as i32
'not of this earth!' _cannot_ be parsed as i64
'not of this earth!' _cannot_ be parsed as i128
'not of this earth!' _cannot_ be parsed as f64
</pre>
=={{header|Scala}}==
Line 5,498 ⟶ 5,614:
</pre>
=={{header|Zig}}==
<syntaxhighlight lang="zig">
const std = @import("std");
const stdout = std.io.getStdOut().writer();
fn isNumeric(str: []const u8) bool {
const num = std.mem.trim(u8, str, "\x20");
_ = std.fmt.parseFloat(f64, num) catch return false;
return true;
}
pub fn main() !void {
const s1 = " 123";
const s2 = " +123";
const s3 = " 12.3";
const s4 = "-12.3";
const s5 = "12e-3";
const s6 = "=12-3";
const s7 = "abcde";
const s8 = "12cde";
const s9 = "NaN";
const s10 = "0xFF";
try stdout.print("Is {s} numeric? {}\n", .{ s1, isNumeric(s1) });
try stdout.print("Is {s} numeric? {}\n", .{ s2, isNumeric(s2) });
try stdout.print("Is {s} numeric? {}\n", .{ s3, isNumeric(s3) });
try stdout.print("Is {s} numeric? {}\n", .{ s4, isNumeric(s4) });
try stdout.print("Is {s} numeric? {}\n", .{ s5, isNumeric(s5) });
try stdout.print("Is {s} numeric? {}\n", .{ s6, isNumeric(s6) });
try stdout.print("Is {s} numeric? {}\n", .{ s7, isNumeric(s7) });
try stdout.print("Is {s} numeric? {}\n", .{ s8, isNumeric(s8) });
try stdout.print("Is {s} numeric? {}\n", .{ s9, isNumeric(s9) });
try stdout.print("Is {s} numeric? {}\n", .{ s10, isNumeric(s10) });
}
</syntaxhighlight>
{{out}}
<pre>
Is 123 numeric? true
Is +123 numeric? true
Is 12.3 numeric? true
Is -12.3 numeric? true
Is 12e-3 numeric? true
Is =12-3 numeric? false
Is abcde numeric? false
Is 12cde numeric? false
Is NaN numeric? true
Is 0xFF numeric? true
</pre>
=={{header|zkl}}==
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