1、基本构成：if 条件： if语句块 else: else语句
2、用于比较运算（大于>）中：a = 0if a > 0: print "a is not 0"else: print 'a is o'
3、用于比较运算中结合逻辑运算符：a = 50if a< 100 and a > 10: print "a is not 0"else: print 'a is false'
4、and的优先级大于or有括号的运算最优先：a = 50if (a< 100 and a > 10 or (a >20 and a<100): print "a is true"else: print 'a is false'
5、结合比较运算操作符: >< == >= <= == != <>：a =90b =100if a>b: print "a is max"else: print 'a is min'
6、结合不等于实例：a =90b =100if a<>b: print "a is max"else: print 'a is min'
7、结合成员关系运算符：In （not in ）：name = 'zhangshan'if 'zhang' not in name: print 'zhang is in name'else: print 'zhang is not in name'
8、elif嵌套结构：if 条件： if语句块elif 条件： elif语句块else: else语句块
9、用于检查多个条件是否满足：number1 = int(input("请输入数字1:"))荏鱿胫协number2 = int(input("请输入数字2:"))if number1 > number2: print "{} 大于 {}".format(number1,number2)elif number2 < number2: print "{} 小于 {}".format(number1,number2)elif number1 == number2: print '%s 等于 %s'%(number1,number2)else: print 'game is over'
10、嵌套语句2：name = input("请输入信蝌怦吩曰息:")if name.endswith('hell泠贾高框o'): if name.startswith('china'): print 'welcome to {}'.format(name) elif name.startswith('japan'): print 'say you {}'.format(name) else: print '输入有误，重新输入'else: print '游戏结束---->'