📅 最后修改于: 2020-11-03 07:09:03 🧑 作者: Mango
运算符是一个符号，告诉编译器执行特定的数学或逻辑操作。 LISP允许对数据进行大量操作，并由各种功能，宏和其他结构支持。
允许对数据进行的操作可以归类为-
下表显示了LISP支持的所有算术运算运算符。假设变量A持有10，变量B持有20，则-
| Operator | Description | Example |
|---|---|---|
| + | Adds two operands | (+A B) will give 30 |
| – | Subtracts second operand from the first | (- A B) will give -10 |
| * | Multiplies both operands | (* A B) will give 200 |
| / | Divides numerator by de-numerator | (/ B A) will give 2 |
| mod,rem | Modulus Operator and remainder of after an integer division | (mod B A )will give 0 |
| incf | Increments operator increases integer value by the second argument specified | (incf A 3) will give 13 |
| decf | Decrements operator decreases integer value by the second argument specified | (decf A 4) will give 9 |
下表显示了LISP支持的所有关系运算符，它们在数字之间进行比较。然而不同于其他语言的关系运算符，LISP比较运算符可能需要两个以上操作数，他们只有数工作。
假设变量A持有10，变量B持有20，则-
| Operator | Description | Example |
|---|---|---|
| = | Checks if the values of the operands are all equal or not, if yes then condition becomes true. | (= A B) is not true. |
| /= | Checks if the values of the operands are all different or not, if values are not equal then condition becomes true. | (/= A B) is true. |
| > | Checks if the values of the operands are monotonically decreasing. | (> A B) is not true. |
| < | Checks if the values of the operands are monotonically increasing. | (< A B) is true. |
| >= | Checks if the value of any left operand is greater than or equal to the value of next right operand, if yes then condition becomes true. | (>= A B) is not true. |
| <= | Checks if the value of any left operand is less than or equal to the value of its right operand, if yes then condition becomes true. | (<= A B) is true. |
| max | It compares two or more arguments and returns the maximum value. | (max A B) returns 20 |
| min | It compares two or more arguments and returns the minimum value. | (min A B) returns 10 |
通用LISP提供了三个逻辑运算符：和或， and不对布尔值进行运算。假设A的值为nil， B的值为5，则-
| Operator | Description | Example |
|---|---|---|
| and | It takes any number of arguments. The arguments are evaluated left to right. If all arguments evaluate to non-nil, then the value of the last argument is returned. Otherwise nil is returned. | (and A B) will return NIL. |
| or | It takes any number of arguments. The arguments are evaluated left to right until one evaluates to non-nil, in such case the argument value is returned, otherwise it returns nil. | (or A B) will return 5. |
| not | It takes one argument and returns t if the argument evaluates to nil. | (not A) will return T. |
按位运算符对位进行运算并执行逐位操作。逐位和，或和与或运算的真值表如下-
| p | q | p and q | p or q | p xor q |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 |
| 0 | 1 | 0 | 1 | 1 |
| 1 | 1 | 1 | 1 | 0 |
| 1 | 0 | 0 | 1 | 1 |
Assume if A = 60; and B = 13; now in binary format they will be as follows:
A = 0011 1100
B = 0000 1101
-----------------
A and B = 0000 1100
A or B = 0011 1101
A xor B = 0011 0001
not A = 1100 0011
下表列出了LISP支持的按位运算符。假设变量A保持60，变量B保持13，则-
| Operator | Description | Example |
|---|---|---|
| logand | This returns the bit-wise logical AND of its arguments. If no argument is given, then the result is -1, which is an identity for this operation. | (logand a b)) will give 12 |
| logior | This returns the bit-wise logical INCLUSIVE OR of its arguments. If no argument is given, then the result is zero, which is an identity for this operation. | (logior a b) will give 61 |
| logxor | This returns the bit-wise logical EXCLUSIVE OR of its arguments. If no argument is given, then the result is zero, which is an identity for this operation. | (logxor a b) will give 49 |
| lognor | This returns the bit-wise NOT of its arguments. If no argument is given, then the result is -1, which is an identity for this operation. | (lognor a b) will give -62, |
| logeqv | This returns the bit-wise logical EQUIVALENCE (also known as exclusive nor) of its arguments. If no argument is given, then the result is -1, which is an identity for this operation. | (logeqv a b) will give -50 |