how to store a value to a variable while in a for loop-CodePudding

I'm programming a calculator.

For example, I have the following:

result = 0
splitted_calculation = ["2", " ", "2"]
for thing in splited_calculation:
    if thing == " ":
        result = result   number
    else:
        number = int(thing)
print(result)

I want that, if the variable in the for loop is an integer, then that value is stored such that I can add the previous integer to the next integer currently in the for loop. However, when I run the code, I always get 0. It seems that the "number = int(thing)" isn't working. Any tips to solve this?

CodePudding user response：

The issue with your code (besides the typo) is that the last digit is ignored. Step through it - in your head, on paper, or with a debugger.

Iterations of the loop. For this example, change it to ['2',' ','3'] for clarity:

SIteration	`thing`	Action	`number`	`result`
1	2	assign it to `number`	2	0
2		add `number` to `result`	2	2
3	3	assign it to `number`	3	2

After the loop, the last digit is just hanging out in number but was never added to result. So result ends up at 2 not 5.

If the format is always "number operator number" there is no need for a loop. Access the values directly from the list:

splitted_calculation = ["2", " ", "2"]
left_number = int(splitted_calculation[0])
right_number = int(splitted_calculation[2])
operator = splitted_calculation[1]
if operator == ' ':
    result = left_number   right_number
elif operator == '-'
    result = left_number - right_number
# repeat for others.

If the formulas are more complex ("2 2 2" for example) you can modify the loop to store the last operator and do the math on the numbers:

splitted_calculation = ["-5", " ", "2", "-", "3"]
result = 0
last_op = " "
for n in splitted_calculation:
    if n in " -*/":
        last_op = n
    else:
        if last_op == ' ': result  = int(n)
        elif last_op == '-': result -= int(n)
        elif last_op == '*': result *= int(n)
        elif last_op == '/': result /= int(n)

Output:

-6

CodePudding user response：

Find Modified Code Below:

result = 0
splited_calculation = ["2", " ", "2"]
for thing in splited_calculation:
    if thing != " ":
       result  = int(thing)

print(result)