如何在 loop 中使用 trimLeft 中？

[jiacai2050]

const line = "line read from somewhere";    
for (std.ascii.spaces) |v| {
    line = std.mem.trimLeft(u8, line, &[_]u8{v});
}

This snippet will report error: cannot assign to constant.

If I change const line to var line, it will report

./src/loc.zig:82:36: error: expected type '[]u8', found '[]const u8'
            line = std.mem.trimLeft(u8, line, &[_]u8{v});

I couldn't understand how to use trimLeft inside a loop, since both its input and output is const, how could I trim a value cascadingly?

Source

• https://ziggit.dev/t/how-to-use-trimleft-inside-a-loop/327

[jiacai2050]

在 ziggit 上已经有人回复了，答案也很简单：

var line: []const u8 = "foo";

The reason why string literals are not slices by default is that a pointer to an array preserves more compile-time information than a slice because a slice has a run-time known length.

之前主要是搞混淆了 const 的位置，

• var line: []const u8 表示 line 可以改变指向
• const line: [] u8 表示 line 不可以改变指向，但是可以改变指向值的内容