I’m trying to allocate some number of bytes to an uninitialized var of type u8 in a different scope, the array can not be const. The compiler keeps complaining about unmatching type:

error: expected type '*const[0:0]u8', found '[]u8' 

What am I doing wrong, how can we do this?

1. Create an empty array, here one of type u8 (a string)

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   <code>var my_array = ""

   </code>

   <code>var my_array = "" </code>

   var my_array = ""
   

2. In another scope, allocate it to match some parameter

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   <code>var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);

   defer arena.deinit();

   const allocator = arena.allocator();

   if (true) {

   my_array = try allocator.alloc(u8, 4);

   defer allocator.free(my_array);

   std.mem.copyForwards(u8, my_array, "okok")

   }

   </code>

   <code>var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator); defer arena.deinit(); const allocator = arena.allocator(); if (true) { my_array = try allocator.alloc(u8, 4); defer allocator.free(my_array); std.mem.copyForwards(u8, my_array, "okok") } </code>

   var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
   defer arena.deinit();
   const allocator = arena.allocator();
   
   if (true) {
     my_array = try allocator.alloc(u8, 4);
     defer allocator.free(my_array);
     std.mem.copyForwards(u8, my_array, "okok")
   }
   

3. When building you get a type error:

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   <code>error: expected type '*const[0:0]u8', found '[]u8'

   </code>

   <code>error: expected type '*const[0:0]u8', found '[]u8' </code>

   error: expected type '*const[0:0]u8', found '[]u8' 
   

However, it works when calling the allocator.alloc on a const array. But then I can not access it in the greater scope.

const my_array = try allocator.alloc(u8, 4);