Python for循环语句

Posted 2021-03-12 Hany博客

Python for 循环语句：遍历任何序列的项目，可以是字符串、列表、元组、字典、集合对象。

 

流程图：

 

第一种：

\'\'\'
for 迭代对象 in 序列:
    代码块(一行语句或多行代码)
\'\'\'

第二种：

\'\'\'
for 迭代对象 in 序列:
    代码块(一行语句或多行代码)
else:
    代码块(一行语句或多行代码)
\'\'\'

 

 示例：

第一种：

for i in range(4):
    print(i)
# 0
# 1
# 2
# 3

# 字符串
strs = "Hello World."
for i in strs:
    print(i,end=" ")
#     H e l l o   W o r l d . 
print()

# 列表
lst = [1,2.3,8+9j,\'abc\',(4,5),{7,8,\'a\'},{\'a\':4}]
for i in lst:
    print(i,end=" ")
#     1 2.3 (8+9j) abc (4, 5) {8, \'a\', 7} {\'a\': 4} 
print()

# 元组
tup = (1,2,3,4,5,6)
for i in tup:
    print(i,end=" ")
#     1 2 3 4 5 6 
print()

# 字典
dic = {\'a\':{\'b\':123},(4,5):\'str\',123:[4,5,6]}
# 键为不可变类型 字符串、元组、数字
for i in dic:
    print(i,end=" ")
#     a (4, 5) 123 
print()

# 集合
set_1 = {1,2.5,\'a\',(7,8,9)}
for i in set_1:
    print(i,end=" ")
#     1 2.5 a (7, 8, 9) 
print()

 

第二种：

for i in range(4):
    print(i)
else:
    print("运行OK")
# 0
# 1
# 2
# 3
# 运行OK

# 字符串
strs = "Hello World."
for i in strs:
    print(i,end=" ")
#     H e l l o   W o r l d . 运行OK
else:
    print("运行OK")
print()

# 列表
lst = [1,2.3,8+9j,\'abc\',(4,5),{7,8,\'a\'},{\'a\':4}]
for i in lst:
    print(i,end=" ")
#     1 2.3 (8+9j) abc (4, 5) {8, \'a\', 7} {\'a\': 4} 运行OK
else:
    print("运行OK")
print()

# 元组
tup = (1,2,3,4,5,6)
for i in tup:
    print(i,end=" ")
#     1 2 3 4 5 6 运行OK
else:
    print("运行OK")
print()

# 字典
dic = {\'a\':{\'b\':123},(4,5):\'str\',123:[4,5,6]}
# 键为不可变类型 字符串、元组、数字
for i in dic:
    print(i,end=" ")
#     a (4, 5) 123 运行OK
else:
    print("运行OK")
print()

# 集合
set_1 = {1,2.5,\'a\',(7,8,9)}
for i in set_1:
    print(i,end=" ")
#     1 2.5 a (7, 8, 9) 运行OK
else:
    print("运行OK")
print()

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2020-02-06