OCAML - 字符串和子字符串

Question

有人可以幫我寫一個函數，檢查一個字符串是否是另一個字符串的子字符串？

（可以有比只有2字符串的更多）

由於

Answer 1

String隨着模塊：

let contains s1 s2 = 
    try 
    let len = String.length s2 in 
    for i = 0 to String.length s1 - len do 
     if String.sub s1 i len = s2 then raise Exit 
    done; 
    false 
    with Exit -> true 

隨着Str模塊，如@barti_ddu所述檢查this topic：

let contains s1 s2 = 
    let re = Str.regexp_string s2 in 
    try 
     ignore (Str.search_forward re s1 0); 
     true 
    with Not_found -> false 

Answer 2

使用電池，您可以使用String.exists。它也存在於ExtLib中：String.exists。

Answer 3

一個String爲基礎的替代cago的回答可能有更好的性能和更低的內存使用率：

let is_substring string substring = 
    let ssl = String.length substring and sl = String.length string in 
    if ssl = 0 || ssl > sl then false else 
    let max = sl - ssl and clone = String.create ssl in 
    let rec check pos = 
     pos <= max && (
     String.blit string pos clone 0 ssl ; clone = substring 
     || check (String.index_from string (succ pos) substring.[0]) 
    ) 
    in    
    try check (String.index string substring.[0]) 
    with Not_found -> false 

Answer 4

String str="hello world"; 


System.out.println(str.contains("world"));//true 

System.out.println(str.contains("world1"));//false