Re: cannot implicitly convert char[] to string

[cym13 via Digitalmars-d-learn]

On Saturday, 15 August 2015 at 11:34:01 UTC, cym13 wrote:

On Saturday, 15 August 2015 at 11:25:20 UTC, vladde wrote:

I made a PR to phobos where I modified `std.format.format`. https://github.com/D-Programming-Language/phobos/pull/3528

However the auto builder fails, with the error message:

runnable/test23.d(1219): Error: cannot implicitly convert expression (format("s = %s", s)) of type char[] to string

The line which fails is `p = std.string.format("s = %s", s);`

I don't understand why I can't convert a char[] to string.

I think it has to do with the fact that string is an alias to immutable(char)[] and you can't implicitely cast an immutable to a regular variable.

I phrased it completely wrong, an example will be better :

    import std.stdio;

    void fun(immutable(int)[] i) {
        i.writeln();
    }

    void main() {
        int[] i = [42];
        fun(i);
    }

Will not compile because there is no certainty that fun() won't
change the array while the following will work

    import std.stdio;

    void fun(immutable(int)[] i) {
        i.writeln();
    }

    void main() {
        int[] i = [42];
        fun(i.dup);

        immutable(int)[] j = [42];
        fun(j);

        immutable(int[]) k = [42];
        fun(k);
    }