# Programming-Idioms

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# Idiom #137 Check if string contains only digits

Set the boolean b to true if the string s contains only characters in the range '0'..'9', false otherwise.

``boolean b = s.matches("[0-9]*");``
``boolean b = s.matches("[0-9]+");``
``B := (for all Char of S => Char in '0' .. '9');``
``#include <string.h>``
``````char b = 0;
int n = strlen(s);
for (int i = 0; i < n; i++) {
if (! (b = (s[i] >= '0' && s[i] <= '9')))
break;
}
``````
``````#include <ctype.h>
#include <stdbool.h>
#include <string.h>``````
``````bool b = true;
const int n = strlen(s);
for (int i = 0; i < n; ++i) {
if (!isdigit(s[i])) {
b = false;
break;
}
}``````
``(def b (every? #(Character/isDigit %) s))``
``````#include <algorithm>
#include <cctype>
#include <string>``````
``````bool b = false;
if (! s.empty() && std::all_of(s.begin(), s.end(), [](char c){return std::isdigit(c);})) {
b = true;
}``````
``bool b = s.All(char.IsDigit);``
``````import std.ascii;
import std.algorithm;``````
``bool b = s.all!isDigit;``
``````std.algorithm.iteration;
std.ascii;``````
``bool b = s.filter!(a => !isDigit(a)).empty;``
``final b = RegExp(r'^[0-9]+\$').hasMatch(s);``
``b =  Regex.match?(~r{\A\d*\z}, s)``
``````{_,Rest} = string:to_integer(S),
B = Rest == "".``````
``````Str = "21334",
[Ch || Ch <- Str, Ch < \$0 orelse Ch > \$9] == [].``````
``````b = .true.
do i=1, len(s)
if (s(i:i) < '0' .or. s(i:i) > '9') then
b = .false.
exit
end if
end do``````
``import "strings"``
``````isNotDigit := func(c rune) bool { return c < '0' || c > '9' }
b := strings.ContainsFunc(s, isNotDigit) ``````
``````b := true
for _, c := range s {
if c < '0' || c > '9' {
b = false
break
}
}``````
``import Data.Char``
``b = all isDigit s``
``var b = /^[0-9]+\$/.test(s);``
``fun String?.isOnlyDigits() = !this.isNullOrEmpty() && this.all { Character.isDigit(it) }``
``````val regex = Regex("[0-9]*")
val b = regex.matches(s)``````
``(setf b (every #'digit-char-p s))``
``b = tonumber(s) ~= nil``
``@import Foundation;``
``````id nodigit=[[NSCharacterSet characterSetWithRange:NSMakeRange('0',10)].invertedSet copy];
BOOL b=![s rangeOfCharacterFromSet:nodigit].length;``````
``\$b = preg_match('/\D/', \$s) !== 1;``
``````var
S: String;
C: Char;
B: Boolean;

for C in S do
begin
B := C in ['0'..'9'];
if not B then Break;
end;
``````
``my \$b = \$s =~ /^\d*\$/;``
``````b = s.isdigit()
``````
``b = s.count("^0-9").zero?``
``let b = s.bytes().all(|c| c.is_ascii_digit());``
``let b = s.chars().all(char::is_numeric);``
``````let chars_are_numeric: Vec<bool> = s.chars()
.map(|c|c.is_numeric())
.collect();
let b = !chars_are_numeric.contains(&false);``````
``def onlyDigits(s: String) = s.forall(_.isDigit) ``
``b := s allSatisfy: #isDigit``
``````Dim x As String = "123456"
Dim b As Boolean = IsNumeric(x)
``````

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