python1

python

if语句

number=23
guess=int(raw_input('Enter an integer : '))
if guess == number:
    print 'Congratulations, you guessed it.' # New block starts here
    print "(but you do not win any prizes!)" # New block ends here
elif guess < number:
    print 'No, it is a little higher than that' # Another block
    # You can do whatever you want in a block ...
else:
    print 'No, it is a little lower than that'
    # you must have guess > number to reach here

print 'Done'
1、raw_input是个内建函数，是指从控制台输入一个数，
注意点：if后百不需要圆括号，但是条件后面要加上一个冒号。

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while语句

number = 23
running = True

while running:
    guess = int(raw_input('Enter an integer : '))

    if guess == number:
        print 'Congratulations, you guessed it.'
        running = False # this causes the while loop to stop
    elif guess < number:
        print 'No, it is a little higher than that'
    else:
        print 'No, it is a little lower than that'
else:
    print 'The while loop is over.'
    # Do anything else you want to do here

print 'Done'

这里需要定义一个退出的条件 running=true;
当我们输入23的时候，running=false，所以不满足条件，因而退出循环，

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for语句

for i in range(1,5):
    print i
else:
    print 'The for loop is over'

range返回一个序列的数。这个序列从第一个数开始到第二个数为止。例如，range(1,5)给出序列[1, 2, 3, 4].