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diff --git a/Doc/Zsh/arith.yo b/Doc/Zsh/arith.yo new file mode 100644 index 000000000..1560c81d3 --- /dev/null +++ b/Doc/Zsh/arith.yo @@ -0,0 +1,73 @@ +texinode(Arithmetic Evaluation)(Conditional Expressions)(Jobs & Signals)(Top) +chapter(Arithmetic Evaluation) +ifzman(\ +sect(Arithmetic Evaluation) +)\ +cindex(arithmetic evaluation) +cindex(evaluation, arithmetic) +An ability to perform integer arithmetic is provided with the builtin tt(let). +findex(let, use of) +Evaluations are performed using em(long) arithmetic. +A leading `tt(0x)' or `tt(0X)' denotes hexadecimal. +Otherwise, numbers are of the form `[var(base)tt(#)]var(n)', +where var(base) is a decimal number between two and thirty-six +representing the arithmetic base and var(n) +is a number in that base (for example, `tt(16#ff)' is 255 in hexadecimal). +If var(base) is omitted +then base 10 is used. For backwards compatibility the form +`tt([)var(base)tt(])var(n)' is also accepted. + +cindex(arithmetic operators) +cindex(operators, arithmetic) +An arithmetic expression uses nearly the same syntax, precedence, and +associativity of expressions in C. +The following operators are supported (listed in decreasing order +of precedence): + +startsitem() +sitem(tt(PLUS() - ! ~ PLUS()PLUS() --))(unary plus/minus, logical NOT, complement, {pre,post}{in,de}crement) +sitem(tt(<< >>))(bitwise shift left, right) +sitem(tt(&))(bitwise AND) +sitem(tt(^))(bitwise XOR) +sitem(tt(|))(bitwise OR) +sitem(tt(**))(exponentiation) +sitem(tt(* / %))(multiplication, division, modulus (remainder)) +sitem(tt(PLUS() -))(addition, subtraction) +sitem(tt(< > <= >=))(comparison) +sitem(tt(== !=))(equality and inequality) +sitem(tt(&&))(logical AND) +sitem(tt(|| ^^))(logical OR, XOR) +sitem(tt(? :))(ternary operator) +sitem(tt(= PLUS()= -= *= /= %= &= ^= |= <<= >>= &&= ||= ^^= **=))(assignment) +sitem(tt(,))(comma operator) +endsitem() + +The operators `tt(&&)', `tt(||)', `tt(&&=)', and `tt(||=)' are short-circuiting, +and only one of the latter two expressions in a ternary operator +is evaluated. Note the precedence of the bitwise AND, OR, +and XOR operators. + +An expression of the form `tt(#\)var(x)' where var(x) is any character +gives the ascii value of this character and an expression of the form +`tt(#)var(foo)' gives the ascii value of the first character of the value +of the parameter var(foo). + +Named parameters and subscripted arrays can be referenced by name within an +arithmetic expression without using the parameter substitution syntax. + +An internal integer representation of a named parameter +can be specified with the tt(integer) builtin. +cindex(parameters, integer) +cindex(integer parameters) +findex(integer, use of) +Arithmetic evaluation is performed on the value of each +assignment to a named parameter declared integer +in this manner. + +Since many of the arithmetic operators require +quoting, an alternative form of the tt(let) command is provided. +For any command which begins with a tt(LPAR()LPAR()), +all the characters until a matching tt(RPAR()RPAR()) +are treated as a quoted expression. +More precisely, `tt(LPAR()LPAR()) ... tt(RPAR()RPAR())' +is equivalent to `tt(let ")...tt(")'. |