Euphoria运算符 - Euphoria教程
Euphoria 提供了一套丰富的运算符操纵变量。我们可以把所有的运算符分成以下几组:
算术运算符
关系运算符
逻辑运算符
赋值运算符
其他运算符
算术运算符:
算术运算符用于在数学表达式中,以同样的方式,它们被用在代数。下表列出了算术运算符:
假设整数变量A=10和变量B=20:
运算符 | 描述 | 示例 |
---|---|---|
+ | Addition - Adds values on either side of the operator | A + B will give 30 |
- | Subtraction - Subtracts right hand operand from left hand operand | A - B will give -10 |
* | Multiplication - Multiplies values on either side of the operator | A * B will give 200 |
/ | Division - Divides left hand operand by right hand operand | B / A will give 2 |
+ | Unary plus - This has no impact on the variable value. | +B gives 20 |
- | Unary minus - This creates a negative value of the given variable. | -B gives -20 |
关系运算符:
Euphoria语言支持的关系运算符
假设整数变量A=10和变量B=20:
运算符 | 描述 | 示例 |
---|---|---|
= | Checks if the value of two operands are equal or not, if yes then condition becomes true. | (A = B) is not true. |
!= | Checks if the value of two operands are equal or not, if values are not equal then condition becomes true. | (A != B) is true. |
> | Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true. | (A > B) is not true. |
< | Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true. | (A < B) is true. |
>= | Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true. | (A >= B) is not true. |
<= | Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true. | (A <= B) is true. |
逻辑运算符:
下表列出了逻辑运算符:
假设布尔变量A=1和变量B=0,则:
运算符 | 描述 | 示例 |
---|---|---|
and | Called Logical AND operator. If both the operands are non zero then then condition becomes true. | (A and B) is false. |
or | Called Logical OR Operator. If any of the two operands are non zero then then condition becomes true. | (A or B) is true. |
xor | Called Logical XOR Operator. Condition is true if one of them is true, if both operands are true or false then condition becomes false. | (A xor B) is true. |
not | Called Logical NOT Operator which negates the result. Using this operator, true becomes false and false becomes true | not(B) is true. |
也可以将这些运算符以外的1或0 数字。其规则是:零表示false 和非零的意味着true。
赋值运算符:
有以下赋值运算符Euphoria 语言支持:
运算符 | 描述 | 例子 |
---|---|---|
= | Simple assignment operator, Assigns values from right side operands to left side operand | C = A + B will assigne value of A + B into C |
+= | Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand | C += A is equivalent to C = C + A |
-= | Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand | C -= A is equivalent to C = C - A |
*= | Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand | C = A is equivalent to C = C A |
/= | Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand | C /= A is equivalent to C = C / A |
&= | Concatenation operator | C &= {2} is same as C = {C} & {2} |
注: 等于符号“=”赋值语句中使用的不是一个操作符,它只是语言的语法的一部分。
其他运算符
很少有其他运算符Euphoria 语言支持。
'&' 操作符:
使用&操作符可以连接,任意两个对象。其结果是一个序列与级联对象的长度的总和相等的长度。
下面的例子:
#!/home/euphoria-4.0b2/bin/eui
sequence a, b, c
a = {1, 2, 3}
b = {4}
c = {1, 2, 3} & {4}
printf(1, "Value of c[1] %d\n", c[1] )
printf(1, "Value of c[2] %d\n", c[2] )
printf(1, "Value of c[3] %d\n", c[3] )
printf(1, "Value of c[4] %d\n", c[4] )
这将产生以下结果:
Value of c[1] 1
Value of c[2] 2
Value of c[3] 3
Value of c[4] 4
Euphoria运算符的优先级:
运算符优先级确定在表达式中的分组。这会影响如何计算一个表达式。某些运算符有比别人更高的优先级,例如,乘法运算符的优先级高于加法运算符:
例如,X=7+3 2;这里x分配13,不是20,因为运算符具有较高优先级,所以先乘以3 * 2 高于 +,然后添加到7。
这里具有最高优先级的运算符出现在上面的表中,那些与最低的出现在底部。在一个表达式,将先评估较高优先级运算符。
分类 | 运算符 | 关联性 |
---|---|---|
Postfix | function/type calls | |
Unary | + - ! not | Right to left |
Multiplicative | * / | Left to right |
Additive | + - | Left to right |
Concatenation | & | Left to right |
Relational | > >= < <= | Left to right |
Equality | = != | Left to right |
Logical AND | and | Left to right |
Logical OR | or | Left to right |
Logical XOR | xor | Left to right |
Comma | , | Left to right |