递增基值python for循环

Question

每次在for循环中循环“I”时如何递增基值？ 逻辑是这样的：

fruits = [bananas, apples, pears]
total_fruits_count = 0

for i in fruits:
    ## some code resolveing fruit count ##
    local_fruit_count = 1
    total_fruits_count + local_fruit_count

print total_fruits_count

有了这个代码，水果总数就变成了0。这怎么可能？在

Answer 1

您需要修改total_fruits_count的值。在

fruits = ["bananas", "apples", "pears"]
total_fruits_count = 0

for i in fruits:
    local_fruit_count = 1
    total_fruits_count += local_fruit_count

print total_fruits_count

在您的原始代码中，您做了total_fruits_count + local_fruit_count，它计算了这两个值的和，但不做任何处理。加号等于快捷键+=将这些值相加并存储在左变量total_fruits_count中。在

Answer 2

这只是计算和并丢弃结果

total_fruits_count + local_fruit_count

您需要=将结果分配回total_fruits_count

^{pr2}$

Answer 3

我认为您可以根据需要使用枚举函数或len

fruits = ["bananas", "apples", "pears"]
for i, fruit in enumerate(fruits):
     print "fruit with index %d is '%s'" % (i, fruit)

total_fruits_count = len(fruits)