Click me to see the sample solution 60. Math Formula Parser Write a Python program to parse math formulas and put parentheses around multiplication and division. Sample data : 4+5*7/2 Expected Output : 4+((5*7)/
2nd_place = "silver" # 错误:以数字开头 user-name = "Bob" # 错误:包含连字符 class = "Math" # 错误:使用关键字 $price = 9.99 # 错误:包含特殊字符 for = "loop" # 错误:使用关键字Python 3 允许使用 Unicode 字符作为标识符,可以用中文作为变量名,非 ASCII 标识符也是允许的了。
In this section, you’re going to code an application to evaluate math expressions on the fly. If you wanted to solve this problem without using eval(), then you’d need to go through the following steps:Parse the input expression. Change the expression’s components into Python objects (...
import cmath 模块---复数运算 import decimal 模块---用于十进制数学计算 python中的float使用双精度的二进制浮点编码来表示的,这种编码导致了小数不能被精确的表示,例如0.1实际上内存中为0.100000000000000001,还有3*0.1 == 0.3 为False. decimal就是为了解决类似的问题的,拥有更高的精确度,能表示更大范围的数字,...
sexpdata is a simple S-expression parser/serializer. It has simple load and dump functions like pickle, json or PyYAML module. >>>fromsexpdataimportloads, dumps >>> loads('("a" "b")') ['a', 'b'] >>>print(dumps(['a','b'])) ("a" "b") ...
import argparse # 创建 ArgumentParser 对象 parser = argparse.ArgumentParser(description="一个简单的命令行程序") # 添加参数 parser.add_argument("name", help="你的名字") parser.add_argument("-a", "--age", type=int, help="你的年龄") # 解析命令行参数 args = parser.parse_args() # 输出结...
polar(algebraic) >>> trigonometric = radius * (cmath.cos(angle) + 1j*cmath.sin(angle)) >>> exponential = radius * cmath.exp(1j*angle) >>> for number in algebraic, geometric, trigonometric, exponential: ... print(format(number, "g")) ... 3+2j 3+2j 3+2j 3+2j All ...
AST(Abstract Syntax Tree),中文抽象语法树,简称语法树(Syntax Tree),是源代码的抽象语法结构的树状表现形式,树上的每个节点都表示源代码中的一种结...
parser.error("Hostname is required") host = args[0] ... From this point on, the rest of the script is the same. We begin by importing only the OptionParser class from our optparse module. We create a usage statement we can give to our parser, and then we define the par...
Python内置了很多标准库,如做数学运算的math, 调用系统功能的sys, 处理正则表达式的re, 操作系统相关功能的os等。我们主要关注两个库: sys sys.argv 处理命令行参数 sys.exit() 退出函数 sys.stdin 标准输入 sys.stderr 标准错误 os os.system()或os.popen() 执行系统命令 ...