addu

Add two unsigned integers, checking for overflow (aka carry).

The overflow is sticky, meaning a sequence of operations can be done and overflow need only be checked at the end.

uint addu(uint x, uint y, bool overflow)
ulong addu(ulong x, ulong y, bool overflow)
ucent addu(ucent x, ucent y, bool overflow)
nothrow @safe @nogc pure pragma(inline, true)
static if(is(ucent))
ucent
addu
()
(
ucent x
,
ucent y
,
ref bool overflow
)

Parameters

x ucent: left operand
y ucent: right operand
overflow bool: set if an overflow occurs, is not affected otherwise

Return Value

Type: ucent

the sum

Examples

for (uint i = 0; i < 10; ++i)
{
    bool overflow;
    immutable uint r = addu (uint.max - i, uint.max - i, overflow);
    assert (r == 2 * (uint.max - i));
    assert (overflow);
}

bool overflow;
assert(addu(2, 3, overflow) == 5);
assert(!overflow);

assert(addu(1, uint.max - 1, overflow) == uint.max);
assert(!overflow);

assert(addu(uint.min, -1, overflow) == uint.max);
assert(!overflow);

assert(addu(uint.max, 1, overflow) == uint.min);
assert(overflow);

overflow = false;
assert(addu(uint.min + 1, -1, overflow) == uint.min);
assert(overflow);

assert(addu(0, 0, overflow) == 0);
assert(overflow);                   // sticky

bool overflow;
assert(addu(2L, 3L, overflow) == 5);
assert(!overflow);

assert(addu(1, ulong.max - 1, overflow) == ulong.max);
assert(!overflow);

assert(addu(ulong.min, -1L, overflow) == ulong.max);
assert(!overflow);

assert(addu(ulong.max, 1, overflow) == ulong.min);
assert(overflow);

overflow = false;
assert(addu(ulong.min + 1, -1L, overflow) == ulong.min);
assert(overflow);

assert(addu(0L, 0L, overflow) == 0);
assert(overflow);                   // sticky

addu

Parameters

Return Value

Examples

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