Python函数返回的奇怪打印输出

Question

I'm a newbie who just starting out. I have been playing around with function and I can't understand why I get the output below from the code below:

Why doesn't it print the return value as well as text from a function in continuous lines, why does the output look like it is looping through the functions twice?

def add(a, b):
    print "ADDING %d + %d" % (a, b)
    return a + b

def subtract(a, b):
    print "SUBTRACTING %d - %d" % (a, b)
    return a - b

def multiply(a, b):
    print "MULTIPLYING %d * %d" % (a, b)
    return a * b

plus = add(1,1)
minus = subtract(1,1)
times = multiply(1,1)

print plus
print minus
print times

The output I get is:

ADDING 1 + 1

SUBTRACTING 1 - 1

MULTIPLYING 1 * 1

2

0

1

Answer 1

Your code is written this way. First you execute all three functions. Then you print the results of all three functions.

plus = add(1,1)          # ADDING 1 + 1
minus = subtract(1,1)    # SUBTRACTING 1 - 1
times = multiply(1,1)    # MULTIPLYING 1 * 1

print plus               # 2
print minus              # 0
print times              # 1

If you want the results interleaved with the calculations, then interleave them.

plus = add(1,1)          # ADDING 1 + 1
print plus               # 2
minus = subtract(1,1)    # SUBTRACTING 1 - 1
print minus              # 0
times = multiply(1,1)    # MULTIPLYING 1 * 1
print times              # 1