Logo

Programming-Idioms

# 96 Check string prefix
Set the boolean b to true if string s starts with prefix prefix, false otherwise.
New implementation

Be concise.

Be useful.

All contributions dictatorially edited by webmasters to match personal tastes.

Please do not paste any copyright violating material.

Please try to avoid dependencies to third-party libraries and frameworks.

Other implementations 
with Ada.Strings.Fixed;
B := Ada.Strings.Fixed.Index (S, Prefix) = S'First;
#include <stdbool.h>
#include <string.h>
bool b = !strncmp(s, prefix, sizeof(prefix)-1);
(require '[clojure.string :refer [starts-with?]])
(def b (starts-with? s prefix))
IDENTIFICATION DIVISION.
PROGRAM-ID. prefix.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 BOOLEAN-B     PIC X.
   88 b-TRUE       VALUE "T".
   88 b-FALSE      VALUE "F".
PROCEDURE DIVISION.
    IF s(1:3) = prefix(1:3)
       SET b-TRUE  TO TRUE
    ELSE
       SET b-FALSE TO TRUE
    END-IF 	 	
STOP RUN.
#include <string>
std::string prefix = "something";
bool b = s.compare(0, prefix.size(), prefix) == 0;
#include <string>
bool b = s.starts_with(prefix);
bool b = s.StartsWith(prefix);
import std.algorithm.searching;
b = s.startsWith(prefix);
var b = s.startsWith(prefix);
String.starts_with?(s,prefix)
B = string:find(S, Prefix) =:= S.
prefix([], _) -> true;
prefix([Ch | Rest1], [Ch | Rest2]) ->
        prefix(Rest1, Rest2);
prefix(_, _) -> false.

prefix("abc", "abcdef").
  logical :: b
  b = index (string, prefix) == 1
import "strings"
b := strings.HasPrefix(s, prefix)
import Data.List
b = prefix `isPrefixOf` s
var b = (s.lastIndexOf(prefix, 0) === 0);
var b = s.startsWith(prefix);
boolean b = s.startsWith(prefix);
val b = s.startsWith(prefix)
(defun check-prefix (s prefix)
 (cond ((> (length prefix) (length s)) Nil)
       ( T ( equal prefix (subseq s 0 (length prefix ))))))

(setf b (check-prefix s prefix))
b = s:find(prefix, 1, true) == 1
b = string.sub(s, 1, #prefix) == prefix
function startswith(text, prefix)
    return text:find(prefix, 1, true) == 1
end

b = startswith(s, prefix)
@import Foundation;
BOOL b=[s hasPrefix:prefix];
$b = (bool) preg_match('#^http#', $s);
b := pos(prefix, s) = 1;
$b = $prefix eq substr($s,0,length($prefix));
b = s.startswith(prefix)
b = s.start_with?(prefix)
let b = s.starts_with(prefix);
val b = s.startsWith(prefix)
b := s beginsWith: prefix
Dim b As Boolean = s.StartsWith(prefix)

Preview