Check if give an array is equal to first elements in another array

[Ali Çehreli via Digitalmars-d-learn]

On 10/15/2014 09:35 PM, MachineCode wrote:
> Is there one function in the Phobos library to check if give an array is
> equal to first elements in another array? e.g, f(a, b) the entire b
> array must match to first elements in a and then return true otherwise
> false, ie:
>
>> a[0 .. b.length] == b
>
> probably there's no such a function (but I wouldn't find bad if there
> was) in the D's library so what's a good name (that'a descriptive) to
> such a function?
>
> btw, what it solves is:
>
>> if(a.length >= b1.length && a[0 .. b1.length] == b1) { ... }
>> if(a.length >= b2.length && a[0 .. b2.length] == b2) { ... }
>
> since if bx.length < a.length is valid I can't remove all the a.length
>  >= bx.length checks otherwise I can have a range violation error

import std.algorithm;

void main()
{
     auto a = [ 1, 42, 100, 7 ];
     auto b = [ 1, 42 ];
     assert(a.startsWith(b));
}

Ali