1、字符串的几种引号
n1 = "catinsky" n1 = 'catinsky' n1 = """catinsky""" n1 = '''catinsky'''
2、字符串的运算
加法: n1 = "catinsky" n2 = "nice" n3 = n1 + n2 print(n3); 乘法: n1 = "catinsky" n4 = n1 * 10 print(n4);
3、运算
#!/usr/bin/env python # -*- conding:utf-8 -*- ''' 1、数字运算 数字的运算: 加法: + 减法: - 乘法: * 除法: / 次方: ** 取余: % 取商: // 2、赋值运算 = 接收赋值运算符 例如:c = a + b += 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 以上结果是值的可以归为一大类。 以下结果是布尔值的可以归为一大类。 3、比较运算 == 等于 != 不等于 <> 不等于,一般不使用,mysql使用此方法。 > 大于 < 小于 >= 大于等于 <= 小于等于 4、逻辑运算 and 且(与) or 或 not 非 例如: ''' user = "catinsky" password = "123" v = user == "catinsky" and password == "123" or user == "cat" and password == "123" print(v) ''' print(v)的结果一定是True。 执行顺序,从左到右计算: True or ==> True True and ==> 继续走 False or ==> 继续走 False and ==> Fales 5、成员运算 in和not in 例如: ''' name = "catinsky" v = "cat" in name print(v)
4、pass与countiue
#!/usr/bin/env python # -*- conding:utf-8 -*- #输出10以内数字,7除外。 #方法1,continue实现。continue不会执行continue后面的代码 count = 1 while count < 11: if count == 7: count = count + 1 continue else: print(count) count = count + 1 print("++++++++++contine用法++++++++++") #方法2,pass实现。pass直接跳过当前。 count_b = 1 while count_b < 11: if count_b == 7: pass else: print(count_b) count_b = count_b + 1 print("++++++++++pass用法++++++++++")