RuleExpression
The following contents are collectively called expression.
The expression is composed by numerical constant and numercal variable using calculation sign.
The expression is composed by character constant and character variable using plus sign.
The expression only have constant.
The expression only have variable.
Function as so on.
The mathematical expression that return value is numerical.
Numerical constant, numerical variable and function of return value compose the mathematic expression by arithmetic calculation and logic calculation.
Composition of mathematic expressions is contained by brackets.
Two mathematic expressions combine a relative expression by relative calculationsign.
Character constant, character variable and function of return string compose the mathematic expression by plus sign.
It can be the composition of many mathematic expression by brackets.
Numerical constant, numerical variable and function of return value compose the mathematic expression by arithmetic calculation and logic calculation.
Character constant, character variable and function of return string compose the mathematic expression by relative calculation.
Logic expression that is composed with logic calculation sign by a few relative expression.
Using logic caculation to compose a few relative expressions. It can be used to operate bit, calculate binary and determine compound condition.
Logic expression can be applicable to any place because its result is mathematic expression of numerical.
If logic expression is false, return 0, otherwise return -1.
Logic expression use "not" calculation, logic "or", logic "and" and "xor" calculation to calculate logically.
To designated value(parameter), repeat to define calculation, let the result to return, this kind of code is called as function.
Function is used as the style of expression. It is different with calculation's mathematic expression, character expression, relative expression and logic expression. Function can save result itself.