如果我在 python 中使用 > 或 != 得到相同的结果

Question

I am learning python. I am creating a program to printing Stars '*' in D Shape using for loop. I am using the following code.

for row in range(7):
    for col in range(5):
        if (col==0 or (col==4 and row!=0 and row!=6)) or ((row==0 or row==6) and (col!=0 and col!=4)):
            print("*", end="")
        else:
            print(end=" ")
    print()

In if statements first section, if I use row>0 and row<6, I get the same result. Now I am confused which operator I should use.

col==4 and row!=0 and row!=6

Answer 1

It doesn't matter.

Since row iterates on range(7) , it can only assume the values of 0, 1, 2, 3, 4, 5 and 6.

• The condition row != 0 applies to 1, 2, 3, 4, 5 and 6.

• The condition row > 0 applies to 1, 2, 3, 4, 5 and 6.

• The condition row != 6 applies to 0, 1, 2, 3, 4 and 5.

• The condition row < 6 applies to 0, 1, 2, 3, 4 and 5.

So in this specific case, you can use them interchangeably (however, I consider > and < to be more readable).

Answer 2

Your rows go from 0 to 6 so:

• row != 0 and row != 6 --> everything except the outer two
• row > 0 and row < 6 ---> everything between the outer two

Answer 3

The reason why row > 0 and row < 6 and row != 0 and row != 6 in this use case results to the same condition is because your row will only get the values of 0 1 2 3 4 5 6.

row > 0 and row < 6 means 1 2 3 4 5

row != 0 and row != 6 means 1 2 3 4 5

Answer 4

Both are ok, but in either case, I'd chain:

0 != row != 6
0 < row < 6