In the IDC expressions you can use almost all C operations except:
complex assignment operations as '+='
Constants are defined more or less like in C, with some minor differences.
There are four type conversion operations:
long(expr) floating point numbers are truncated during conversion
char(expr)
float(expr)
__int64(expr)
However, explicit type conversions are rarely required because all type conversions are made automatically:
- addition:
if both operands are strings,
string addition is performed (strings are concatenated);
if both operands are objects,
object combination is performed (a new object is created)
if floating point operand exists,
both operands are converted to floats;
otherwise
both operands are converted to longs;
- subtraction/multiplication/division:
if floating point operand exists,
both operands are converted to floats;
if both operands are objects and the operation is subtraction,
object subtraction is performed (a new object is created)
otherwise
both operands are converted to longs;
- comparisons (==,!=, etc):
if both operands are strings, string comparison is performed;
if floating point operand exists,
both operands are converted to floats;
otherwise
both operands are converted to numbers;
- all other operations:
operand(s) are converted to longs;
If any of the long operands is 64bit, the other operand is converted to 64bit too.
There is one notable exception concerning type conversions: if one operand is a string and the other is zero (0), then a string operation is performed. Zero is converted to an empty string in this case.
The & operator is used to take a reference to a variable. References themselves cannot be modified once created. Any assignment to them will modify the target variable. For example:
auto x, r;
r = &x;
r = 1; // x is equal to 1 now
References to references are immediately resolved:
auto x, r1, r2;
r1 = &x;
r2 = &r1; // r2 points to x
Since all non-object arguments are passed to functions by value, references are a good way to pass arguments by reference.
