1. If statements

number = 10
if number < 20:
    print('right')
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  • Description:If you use an if statement, if there is only one statement, the block can be written directly to the right of the colon “:”, as in the following code
number = 10
if number < 20:print('right')
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2. if… else

a = -9
if a > 0:
    b = a
else:
    b = -a
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I could just write it as

a = -9
b = a if a > 0 else -a
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3. if… elif… else

number = 1
if number == 1:
    print('1 flower, you are the only one for me! ')
elif number == 3:
    print('3朵，i love you')
else:
    print('number')
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Conditional expressions

  • In program development, it is often conditional to assign values according to the results of expressions. For example, to return two words with a large number of characters, use the following if statement.
a = 10
b = 6
if a > b:
    r = a
else:
    r = b
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The above code can be simplified using conditional expressions as follows:

a = 10
b = 6
r = a if a > b elseWhen b uses a conditional expression, it evaluates the intermediate condition (a > b) first and returns the result if trueifThe value on the left side of the statement, otherwise returnselseThe right-hand value.Copy the code