设为首页收藏本站
查看: 66|回复: 0

[PHP] Python运算符

[复制链接]

论坛元老

Rank: 6Rank: 6

积分
34274
主题
17031
UID
1347
M币
67
贡献
17176

  • 发表于 2017-5-14 02:44:00 | 显示全部楼层 |阅读模式
    什么是运算符?
    本章节主要说明Python的运算符。举个简单的例子 4 +5 = 9 。 例子中,4和5被称为操作数,"+"号为运算符。
    Python语言支持以下类型的运算符:
    算术运算符
    比较(关系)运算符
    赋值运算符
    逻辑运算符
    位运算符
    成员运算符
    身份运算符
    运算符优先级
    接下来让我们一个个来学习Python的运算符。
    Python算术运算符
    以下假设变量a为10,变量b为20:
    运算符
    描述
    实例
    + 加 - 两个对象相加 a + b 输出结果 30
    - 减 - 得到负数或是一个数减去另一个数 a - b 输出结果 -10
    * 乘 - 两个数相乘或是返回一个被重复若干次的字符串 a * b 输出结果 200
    / 除 - x除以y b / a 输出结果 2
    % 取模 - 返回除法的余数 b % a 输出结果 0
    ** 幂 - 返回x的y次幂 a**b 输出结果 20
    // 取整除 - 返回商的整数部分 9//2 输出结果 4 , 9.0//2.0 输出结果 4.0
    以下实例演示了Python所有算术运算符的操作:
    #!/usr/bin/python a = 21 b = 10 c = 0 c = a + b print "Line 1 - Value of c is ", c c = a - b print "Line 2 - Value of c is ", c c = a * b print "Line 3 - Value of c is ", c c = a / b print "Line 4 - Value of c is ", c c = a % b print "Line 5 - Value of c is ", c a = 2 b = 3 c = a**b print "Line 6 - Value of c is ", c a = 10 b = 5 c = a//b print "Line 7 - Value of c is ", c
    以上实例输出结果:
    Line 1 - Value of c is 31 Line 2 - Value of c is 11 Line 3 - Value of c is 210 Line 4 - Value of c is 2 Line 5 - Value of c is 1 Line 6 - Value of c is 8 Line 7 - Value of c is 2
    Python比较运算符
    以下假设变量a为10,变量b为20:
    运算符
    描述
    实例
    == 等于 - 比较对象是否相等 (a == b) 返回 False。
    != 不等于 - 比较两个对象是否不相等 (a != b) 返回 true.
    不等于 - 比较两个对象是否不相等 (a  b) 返回 true。这个运算符类似 != 。
    > 大于 - 返回x是否大于y (a > b) 返回 False。
    >= 大于等于 - 返回x是否大于等于y。 (a >= b) 返回 False。
    以下实例演示了Python所有比较运算符的操作:
    #!/usr/bin/python a = 21 b = 10 c = 0 if ( a == b ): print "Line 1 - a is equal to b" else: print "Line 1 - a is not equal to b" if ( a != b ): print "Line 2 - a is not equal to b" else: print "Line 2 - a is equal to b" if ( a  b ): print "Line 3 - a is not equal to b" else: print "Line 3 - a is equal to b" if ( a [b] b ): print "Line 5 - a is greater than b" else: print "Line 5 - a is not greater than b" a = 5; b = 20; if ( a = a ): print "Line 7 - b is either greater than or equal to b" else: print "Line 7 - b is neither greater than nor equal to b" 以上实例输出结果: Line 1 - a is not equal to b Line 2 - a is not equal to b Line 3 - a is not equal to b Line 4 - a is not less than b Line 5 - a is greater than b Line 6 - a is either less than or equal to b Line 7 - b is either greater than or equal to b
    Python赋值运算符
    以下假设变量a为10,变量b为20:
    运算符
    描述
    实例
    = 简单的赋值运算符 c = a + b 将 a + b 的运算结果赋值为 c
    += 加法赋值运算符 c += a 等效于 c = c + a
    -= 减法赋值运算符 c -= a 等效于 c = c - a
    *= 乘法赋值运算符 c *= a 等效于 c = c * a
    /= 除法赋值运算符 c /= a 等效于 c = c / a
    %= 取模赋值运算符 c %= a 等效于 c = c % a
    **= 幂赋值运算符 c **= a 等效于 c = c ** a
    //= 取整除赋值运算符 c //= a 等效于 c = c // a
    以下实例演示了Python所有赋值运算符的操作:
    #!/usr/bin/python a = 21 b = 10 c = 0 c = a + b print "Line 1 - Value of c is ", c c += a print "Line 2 - Value of c is ", c c *= a print "Line 3 - Value of c is ", c c /= a print "Line 4 - Value of c is ", c c = 2 c %= a print "Line 5 - Value of c is ", c c **= a print "Line 6 - Value of c is ", c c //= a print "Line 7 - Value of c is ", c 以上实例输出结果: Line 1 - Value of c is 31 Line 2 - Value of c is 52 Line 3 - Value of c is 1092 Line 4 - Value of c is 52 Line 5 - Value of c is 2 Line 6 - Value of c is 2097152 Line 7 - Value of c is 99864
    Python位运算符
    按位运算符是把数字看作二进制来进行计算的。Python中的按位运算法则如下:
    运算符
    描述
    实例
    & 按位与运算符 (a & b) 输出结果 12 ,二进制解释: 0000 1100
    | 按位或运算符 (a | b) 输出结果 61 ,二进制解释: 0011 1101
    ^ 按位异或运算符 (a ^ b) 输出结果 49 ,二进制解释: 0011 0001
    ~ 按位取反运算符 (~a ) 输出结果 -61 ,二进制解释: 1100 0011, 在一个有符号二进制数的补码形式。
    >> 右移动运算符 a >> 2 输出结果 15 ,二进制解释: 0000 1111
    以下实例演示了Python所有位运算符的操作:
    #!/usr/bin/python a = 60 # 60 = 0011 1100 b = 13 # 13 = 0000 1101 c = 0 c = a & b; # 12 = 0000 1100 print "Line 1 - Value of c is ", c c = a | b; # 61 = 0011 1101 print "Line 2 - Value of c is ", c c = a ^ b; # 49 = 0011 0001 print "Line 3 - Value of c is ", c c = ~a; # -61 = 1100 0011 print "Line 4 - Value of c is ", c c = a > 2; # 15 = 0000 1111 print "Line 6 - Value of c is ", c
    以上实例输出结果:

    Line 1 - Value of c is 12
    Line 2 - Value of c is 61
    Line 3 - Value of c is 49
    Line 4 - Value of c is -61
    Line 5 - Value of c is 240
    Line 6 - Value of c is 15

    Python逻辑运算符
    Python语言支持逻辑运算符,以下假设变量a为10,变量b为20:
    运算符
    描述
    实例
    and 布尔"与" - 如果x为False,x and y返回False,否则它返回y的计算值。 (a and b) 返回 true。
    or 布尔"或" - 如果x是True,它返回True,否则它返回y的计算值。 (a or b) 返回 true。
    not 布尔"非" - 如果x为True,返回False。如果x为False,它返回True。 not(a and b) 返回 false。
    以下实例演示了Python所有逻辑运算符的操作:
    #!/usr/bin/python a = 10 b = 20 c = 0 if ( a and b ): print "Line 1 - a and b are true" else: print "Line 1 - Either a is not true or b is not true" if ( a or b ): print "Line 2 - Either a is true or b is true or both are true" else: print "Line 2 - Neither a is true nor b is true" a = 0 if ( a and b ): print "Line 3 - a and b are true" else: print "Line 3 - Either a is not true or b is not true" if ( a or b ): print "Line 4 - Either a is true or b is true or both are true" else: print "Line 4 - Neither a is true nor b is true" if not( a and b ): print "Line 5 - a and b are true" else: print "Line 5 - Either a is not true or b is not true" 以上实例输出结果: Line 1 - a and b are true Line 2 - Either a is true or b is true or both are true Line 3 - Either a is not true or b is not true Line 4 - Either a is true or b is true or both are true Line 5 - a and b are true
    Python成员运算符
    除了以上的一些运算符之外,Python还支持成员运算符,测试实例中包含了一系列的成员,包括字符串,列表或元组。
    运算符
    描述
    实例
    in 如果在指定的序列中找到值返回True,否则返回False。 x 在 y序列中 , 如果x在y序列中返回True。
    not in 如果在指定的序列中没有找到值返回True,否则返回False。 x 不在 y序列中 , 如果x不在y序列中返回True。
    以下实例演示了Python所有成员运算符的操作:
    #!/usr/bin/python a = 10 b = 20 list = [1, 2, 3, 4, 5 ]; if ( a in list ): print "Line 1 - a is available in the given list" else: print "Line 1 - a is not available in the given list" if ( b not in list ): print "Line 2 - b is not available in the given list" else: print "Line 2 - b is available in the given list" a = 2 if ( a in list ): print "Line 3 - a is available in the given list" else: print "Line 3 - a is not available in the given list"
    以上实例输出结果:

    Line 1 - a is not available in the given list
    Line 2 - b is not available in the given list
    Line 3 - a is available in the given list

    Python身份运算符
    身份运算符用于比较两个对象的存储单元
    运算符
    描述
    实例
    is is是判断两个标识符是不是引用自一个对象 x is y, 如果 id(x) 等于 id(y) , is 返回结果 1
    is not is not是判断两个标识符是不是引用自不同对象 x is not y, 如果 id(x) 不等于 id(y). is not返回结果 1
    以下实例演示了Python所有身份运算符的操作:
    #!/usr/bin/python a = 20 b = 20 if ( a is b ): print "Line 1 - a and b have same identity" else: print "Line 1 - a and b do not have same identity" if ( id(a) == id(b) ): print "Line 2 - a and b have same identity" else: print "Line 2 - a and b do not have same identity" b = 30 if ( a is b ): print "Line 3 - a and b have same identity" else: print "Line 3 - a and b do not have same identity" if ( a is not b ): print "Line 4 - a and b do not have same identity" else: print "Line 4 - a and b have same identity"
    以上实例输出结果:

    Line 1 - a and b have same identity
    Line 2 - a and b have same identity
    Line 3 - a and b do not have same identity
    Line 4 - a and b do not have same identity

    Python运算符优先级
    以下表格列出了从最高到最低优先级的所有运算符:
    运算符
    描述
    ** 指数 (最高优先级)
    ~ + - 按位翻转, 一元加号和减号 (最后两个的方法名为 +@ 和 -@)
    * / % // 乘,除,取模和取整除
    + - 加法减法
    >>
    & 位 'AND'
    ^ | 位运算符
    >= 比较运算符
    == != 等于运算符
    = %= /= //= -= += *= **= 赋值运算符
    is is not 身份运算符
    in not in 成员运算符
    not or and 逻辑运算符
    以下实例演示了Python所有运算符优先级的操作:
    #!/usr/bin/python a = 20 b = 10 c = 15 d = 5 e = 0 e = (a + b) * c / d #( 30 * 15 ) / 5 print "Value of (a + b) * c / d is ", e e = ((a + b) * c) / d # (30 * 15 ) / 5 print "Value of ((a + b) * c) / d is ", e e = (a + b) * (c / d); # (30) * (15/5) print "Value of (a + b) * (c / d) is ", e e = a + (b * c) / d; # 20 + (150/5) print "Value of a + (b * c) / d is ", e
    以上实例输出结果:
    Value of (a + b) * c / d is 90
    Value of ((a + b) * c) / d is 90
    Value of (a + b) * (c / d) is 90
    Value of a + (b * c) / d is 50
    回复

    使用道具 举报

    您需要登录后才可以回帖 登录 | 立即注册

    本版积分规则

    在我站开通SVIP可同时获得17个站点VIP资源 立即登录 立即注册
    快速回复 返回顶部 返回列表