Python: Reads a given expression and evaluates it
Python Regular Expression: Exercise-52 with Solution
Write a Python program that reads a given expression and evaluates it.
Terms and conditions:
The expression consists of numerical values, operators and parentheses, and the ends with '='.
The operators includes +, -, *, / where, represents, addition, subtraction, multiplication and division.
When two operators have the same precedence, they are applied to left to right.
You may assume that there is no division by zero.
All calculation is performed as integers, and after the decimal point should be truncated
Length of the expression will not exceed 100.
-1 × 10 9 ≤ intermediate results of computation ≤ 10 9
Sample Solution:-
Python Code:
#https://bit.ly/2lxQysi
import re
print("Input number of data sets:")
class c(int):
def __add__(self,n):
return c(int(self)+int(n))
def __sub__(self,n):
return c(int(self)-int(n))
def __mul__(self,n):
return c(int(self)*int(n))
def __truediv__(self,n):
return c(int(int(self)/int(n)))
for _ in range(int(input())):
print("Input an expression:")
print(eval(re.sub(r'(\d+)',r'c(\1)',input()[:-1])))
Sample Output:
Input number of data sets: 2 Input an expression: 4-2*3= -2 Input an expression: 4*(8+4+3)= 60
Flowchart:
Python Code Editor:
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Python: Tips of the Day
Find current directory and file's directory:
To get the full path to the directory a Python file is contained in, write this in that file:
import os dir_path = os.path.dirname(os.path.realpath(__file__))
(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
- The os and os.path modules.
- The __file__ constant
- os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
- os.path.dirname(path) (returns "the directory name of pathname path")
- os.getcwd() (returns "a string representing the current working directory")
- os.chdir(path) ("change the current working directory to path")
Ref: https://bit.ly/3fy0R6m
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