python元组打包和解包过程详解
时间：2022-07-23 10:00:33|栏目：Python代码|点击： 次
1、在将多个以逗号分隔的值赋给一个变量时，多个值被打包成一个元组类型。当我们将一个元组赋给多个变量时，它将解包成多个值，然后分别将其赋给相应的变量。
# 打包 a = 1, 10, 100 print(type(a), a) # <class 'tuple'> (1, 10, 100) # 解包 i, j, k = a print(i, j, k) # 1 10 100
2、解包时，如果解包出来的元素数目与变量数目不匹配，就会引发ValueError异常。错误信息为：too many values to unpack（解包的值太多）或not enough values to unpack（解包的值不足）。
a = 1, 10, 100, 1000 # i, j, k = a # ValueError: too many values to unpack (expected 3) # i, j, k, l, m, n = a # ValueError: not enough values to unpack (expected 6, got 4)
知识点扩充：
python之打包，解包
#coding:utf-8
#字符串，列表，元组打包与解包
aString = 'abc'
aList = [1, 2, 3]
aTuple = 'a', 'A', 1
print('Unpacking string......')
first, second, third = aString
print("string values:", first, second, third)
print('\nUnpacking list......')
first, second, third = aList
print("string values:", first, second, third)
print('\nUnpacking tuple......')
first, second, third = aTuple
print("string values:", first, second, third)
#swapping two values
x = 3
y = 4
print('\nBefore swapping: x = %d,y =%d' % (x, y))
#首先将右边的部分打包成一个元组，即（4，3），而后解包指派给变量x,y
x, y = y, x #swap Variables
print('After swapping: x = %d, y = %d' % (x, y))
