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version 2.104.0

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Function core.checkedint.adds

Add two signed integers, checking for overflow.

int adds (
  int x,
  int y,
  ref bool overflow
);

long adds (
  long x,
  long y,
  ref bool overflow
);

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

Parameters

NameDescription
x left operand
y right operand
overflow set if an overflow occurs, is not affected otherwise

Returns

the sum

Example

bool overflow;
writeln(adds(2, 3, overflow)); // 5
assert(!overflow);

writeln(adds(1, int.max - 1, overflow)); // int.max
assert(!overflow);

writeln(adds(int.min + 1, -1, overflow)); // int.min
assert(!overflow);

writeln(adds(int.max, 1, overflow)); // int.min
assert(overflow);

overflow = false;
writeln(adds(int.min, -1, overflow)); // int.max
assert(overflow);

writeln(adds(0, 0, overflow)); // 0
assert(overflow);                   // sticky

Example

bool overflow;
writeln(adds(2L, 3L, overflow)); // 5
assert(!overflow);

writeln(adds(1L, long.max - 1, overflow)); // long.max
assert(!overflow);

writeln(adds(long.min + 1, -1, overflow)); // long.min
assert(!overflow);

writeln(adds(long.max, 1, overflow)); // long.min
assert(overflow);

overflow = false;
writeln(adds(long.min, -1, overflow)); // long.max
assert(overflow);

writeln(adds(0L, 0L, overflow)); // 0
assert(overflow);                   // sticky

Authors

Walter Bright

License

Boost License 1.0