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main.zig
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main.zig
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const std = @import("std");
const print = std.debug.print;
const testing = std.testing;
const assert = std.debug.assert;
// base is base of number system
// mem[] is the number in the base number system
// we do not need to use length of the buffer as function arguments
// NOTE
// - This pattern is, because mem_arrray is actually an array
// var mem_array = [_]u32{ 1, 2, 3 };
// var mem_ref: []u32 = &mem_array;
// * For convenienc we use &mem_array directly
//assume base >= 0
fn isValidNumber(mem: []u32, base: u32) bool {
for (mem) |m_el| {
if (m_el >= base)
return false;
}
return true;
}
fn isNotNull(mem: []const u32) bool {
for (mem) |m_el| {
if (m_el != 0) {
return true;
}
}
return false;
}
// on successfull addition return true, otherwise false
fn add(mem: []u32, base: u32) bool {
var carry = false;
var index: u32 = @intCast(u32, mem.len - 1);
while (index > 0) : (index -= 1) {
var added_val = mem[index] + 1;
if (added_val == base) {
carry = true;
} else {
mem[index] = added_val;
break;
}
}
// prevent index underflow
if (index == 0 and carry == true and mem[index] + 1 == base) {
return false; // could not increase anymore
}
// zero out numbers right of the index
if (carry == true) {
assert(index < mem.len - 1);
index += 1;
while (index < mem.len) : (index += 1) {
mem[index] = 0;
}
}
return true;
}
test "isValidNumber" {
const base: u32 = 4;
var mem_array = [_]u32{ 1, 2, 3 };
var is_val_nr = isValidNumber(&mem_array, base);
try testing.expectEqual(true, is_val_nr);
}
test "isNull" {
var mem_array1 = [_]u32{ 0, 0, 0 };
var is_not_null = isNotNull(&mem_array1);
try testing.expectEqual(false, is_not_null);
var mem_array2 = [_]u32{ 1, 1, 1 };
is_not_null = isNotNull(&mem_array2);
try testing.expectEqual(true, is_not_null);
}
test "add" {
const base: u32 = 4;
var mem_array = [_]u32{ 1, 2, 3 };
const result = add(&mem_array, base);
const exp_mem_array = [_]u32{ 1, 3, 0 };
try testing.expectEqual(exp_mem_array, mem_array);
try testing.expectEqual(true, result);
mem_array = [_]u32{ 3, 3, 3 };
const result2 = add(&mem_array, base);
try testing.expectEqual(mem_array, mem_array);
try testing.expectEqual(false, result2);
}