The OpenD Programming Language

subs

Subtract two signed integers, checking for overflow.

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

  1. int subs(int x, int y, bool overflow)
  2. long subs(long x, long y, bool overflow)
    nothrow @safe @nogc pure pragma(inline, true)
    long
    subs
    ()
    (
    long x
    ,
    long y
    ,
    ref bool overflow
    )
  3. cent subs(cent x, cent y, bool overflow)

Parameters

x long

left operand

y long

right operand

overflow bool

set if an overflow occurs, is not affected otherwise

Return Value

Type: long

the difference

Examples

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

assert(subs(1L, -long.max + 1, overflow) == long.max);
assert(!overflow);

assert(subs(long.min + 1, 1, overflow) == long.min);
assert(!overflow);

assert(subs(-1L, long.min, overflow) == long.max);
assert(!overflow);

assert(subs(long.max, -1, overflow) == long.min);
assert(overflow);

overflow = false;
assert(subs(long.min, 1, overflow) == long.max);
assert(overflow);

assert(subs(0L, 0L, overflow) == 0);
assert(overflow);                   // sticky
bool overflow;
assert(subs(2, -3, overflow) == 5);
assert(!overflow);

assert(subs(1, -int.max + 1, overflow) == int.max);
assert(!overflow);

assert(subs(int.min + 1, 1, overflow) == int.min);
assert(!overflow);

assert(subs(int.max, -1, overflow) == int.min);
assert(overflow);

overflow = false;
assert(subs(int.min, 1, overflow) == int.max);
assert(overflow);

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

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