How to solve an equation from input expression?

Question

The input expression has to be in a + b and a - b form and the question asks to solve those equation.

(there is space before and after + and -)

So an example would be:

expression: 2.7 + 1000
1002.7

I only got to this point:

import math

text = input("expression: ")

This appears to be a homework or challenge question. What specific requirements do you have for valid solutions? What have you tried to actually evaluate the expression? You may also want to take a look at the [Open letter to students with homework problems](https://softwareengineering.meta.stackexchange.com/questions/6166/open-letter-to-students-with-homework-problems). — MisterMiyagi, Jun 20 '20 at 06:53

score 1 · Answer 1 · answered Jun 20 '20 at 06:36

1

You can do this if we are guaranteed that the expression contains space before and after the "-" or "+"

import math

text = input("expression: ")

expression_list = text.split()

print(expression_list)

if expression_list[1] == '-':
    print(float(expression_list[0]) - float(expression_list[2]))

Similarly, you can do it for addition, multiplication and division as well.

answered Jun 20 '20 at 06:36

Usama

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User input is **never** guaranteed – Marcin Orlowski Jun 20 '20 at 06:37
1

@MarcinOrlowski The questioner has written that there is a format for the input. So, I guess this will work for this particular question. – Usama Jun 20 '20 at 06:41
For testing purposes or for this question - yes. IRL - no. User can i. E. unintentionally make a typo - and without any validation /sanitization you may end up doomed. – Marcin Orlowski Jun 20 '20 at 14:33

score 0 · Answer 2 · answered Jun 20 '20 at 06:36

0

You can use the eval() method. This is a way of literally running expressions.

answered Jun 20 '20 at 06:36

Shrey

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score -1 · Answer 3 · answered Jun 20 '20 at 06:41

-1

One Simple solution for you.

import math
text = input("Expression: ")
output = eval(text)
print("Answer : ", output)

I have tested + - * / these four. try more. Read about eval Function

answered Jun 20 '20 at 06:41

Vignesh

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I did not learn eval Function so I cannot answer the question with eval... – bang21 Jun 20 '20 at 06:49
did you read search string? – Vignesh Jun 20 '20 at 06:52

How to solve an equation from input expression?

3 Answers3