Python mathematical expression evaluation-CodePudding

I was trying to solve a random problem, I used a relation that I made, when I've come to implement it in python it give me different results than the one that I calculated, so I tried to change.

the thing is I don't get how does python see each one!!?

those two expressions here give different results sometimes:

Here's an example:

rows, columns = 4, 4

for row in range(2, rows 1):
    for column in range(1, columns 1):
        print('*'*15)
        result = ((column 1)//2) * ((row 1)//2)
        f_result = (column 1)//2 * (row 1)//2

        print('>> normal expression:', (column 1)//2, (row 1)//2)
        print('>> second expression:', ((column 1)//2), ((row 1)//2))
        print('>>               row:', row)
        print('>>            column:', column)
        print('>>           Results:', result, f_result)
    print()

The results:

CodePudding user response：

You need to understand operator precedence first Check out this link this

for the expression

((col 1)//2) * ((row 1)//2) = (col 1)//2 * (row 1)//2

((col 1)//2) * ((row 1)//2) = ((4 1)//2) * ((4 1)//2)
                            = (5//2)*(5//2)
                            = 2 * 2
                            = 4

(col 1)//2 * (row 1)//2 = (4 1)//2 * (4 1)//2
                        = 5//2 * 5//2
                        = 2 * 5//2
                        = 10//2 (as * has higher precedence than //)
                        = 5