我试图弄清楚这些临时变量的含义

Question

def genfibon(n):      #fib sequence until n
   a=1
   b=1
   for i in range n:
      yield a
      t=a
      a=b
      b=t+b        

有人能解释t变量吗？它看起来像t=a所以a=b然后b=t因为a=b和a=t。b=t+b是怎么做的？你知道吗

Answer 1

假设a=2，b=3。你知道吗

t = a # now t = 2
a = b # now a = 3, but t is unchanged
b = t + b # now b = 5

关键是第二部分。t = a表示t获得与a相同的值。这并不意味着t和a现在都是一回事。你知道吗

您可以在Python提示符中尝试：

a = 3
b = a
a = 5
print(b) # still 3

Answer 2

这叫做变量交换。如何替换变量的值？你知道吗

正如@smarx所说，当a = 2和b = 3时，如何使之a = 3和b = 2？你知道吗

当您执行a = 3时，a（2）的旧值丢失，因此您不知道用什么来设置b。所以我们把它存储在一个临时变量（t）中。你知道吗

所以

t = a //(saves 2 in t)
a = b //(now both a and b have same values)
b = t //(b gets the old value of a)
// now a = old value of b 
// and b = old value of a.

瞧，变量互换了。你知道吗

好吧，那就是交换。在本规范中仅部分使用。最后一条语句b = t + b代码所做的是，将a的旧值与b相加（而不是替换它）。为什么？将前面的2相加，得到斐波那契数列中的下一个数。你知道吗

2，3，5是斐波那契序列，因为5=2+3（给定2和3是种子值）。这正是这段代码要做的。你知道吗

Answer 3

在你的第一次跑步中

yield a # will return 1 
t = a  # which is 1
a = b  # which is 1
b = t + b  # which is 2 as t = 1 and b = 1 

在你的第二次跑步中

yield a # will return 1 
t = a  # which is 1
a = b  # which is 2
b = t + b  # which is 3 as t = 1 and b = 2

在你的第三次跑步中

yield a # will return 2 
t = a  # which is 2
a = b  # which is 3
b = t + b  # which is 5 as t = 2 and b = 3   

在你的第四次跑步中

yield a # will return 3 
t = a  # which is 3
a = b  # which is 5
b = t + b  # which is 8 as t = 3 and b = 5

等等。。。你知道吗