zig

fork of https://codeberg.org/ziglang/zig
Log | Files | Refs | README | LICENSE

error_union_parsing_u64.zig (851B) - Raw

      1 const std = @import("std");
      2 const maxInt = std.math.maxInt;
      3 
      4 pub fn parseU64(buf: []const u8, radix: u8) !u64 {
      5     var x: u64 = 0;
      6 
      7     for (buf) |c| {
      8         const digit = charToDigit(c);
      9 
     10         if (digit >= radix) {
     11             return error.InvalidChar;
     12         }
     13 
     14         // x *= radix
     15         var ov = @mulWithOverflow(x, radix);
     16         if (ov[1] != 0) return error.OverFlow;
     17 
     18         // x += digit
     19         ov = @addWithOverflow(ov[0], digit);
     20         if (ov[1] != 0) return error.OverFlow;
     21         x = ov[0];
     22     }
     23 
     24     return x;
     25 }
     26 
     27 fn charToDigit(c: u8) u8 {
     28     return switch (c) {
     29         '0'...'9' => c - '0',
     30         'A'...'Z' => c - 'A' + 10,
     31         'a'...'z' => c - 'a' + 10,
     32         else => maxInt(u8),
     33     };
     34 }
     35 
     36 test "parse u64" {
     37     const result = try parseU64("1234", 10);
     38     try std.testing.expect(result == 1234);
     39 }
     40 
     41 // test