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

Parameters

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

Return Value

Type: uint

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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