Zig by Example: Slices
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Slices are a special kind of pointer that reference a contiguous subset of elements in a sequence. |
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const std = @import("std"); const print = std.debug.print; |
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The easiest way to understand slices is to think of them as a single-item pointer plus a length. The pointer tells you where the slice begins and the length tells you its size. |
const Slice = []bool; |
pub fn main() !void { |
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Here, we define a slice using the |
var array = [5]i32{ 1, 2, 3, 4, 5 }; const end: usize = 4; const slice = array[1..end]; |
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Functionally, slices are very similar to arrays. You can get their length, index into them, and iterate over them. |
print("len: {}\n", .{slice.len}); print("first: {}\n", .{slice[0]}); for (slice) |elem| { print("elem: {}\n", .{elem}); } |
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All slices must have a runtime-known length. If, instead, their lengths are compile-time known, the compiler will convert the slice into a single-item array pointer for us. |
const ptr: *[3]i32 = array[1..4]; |
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In practice, single-item array pointers are just like slices. The only real difference is that with array pointers, bounds checking occurs at compile-time. |
print("len: {}\n", .{ptr.len}); print("first: {}\n", .{ptr[0]}); for (ptr) |elem| { print("elem: {}\n", .{elem}); } } |
$ zig run slices.zig len: 3 first: 2 elem: 2 elem: 3 elem: 4 len: 3 first: 2 elem: 2 elem: 3 elem: 4 |
Next example: While.