for 循环：
for 循环用于迭代序列（即列表、元组、字典、集合或字符串）。
语法：
对于序列中的变量
示例：
txt = '1234' for num in txt: print(num,end=' ') output: 1 2 3 4
如果条件：
if 语句的工作原理是检查表达式以查看是否满足条件，并根据获得的输出返回一个值。
syntax: if condition: if condition is true else: if condition is false
示例
x=20 if x>=20: print(x is within 20) else : print(x is above the limit) output: x is within 20
txt = '12a4' for num in txt: if num>='0' and num<='9': print(num,end=' ') else: print('not decimal',end=' ') output: 1 2 not decimal 4 above code is the example of combines if and for.
name = input(“请输入您的名字：”)
打印（姓名）
名称中的字母：
print(字母表, end=’*’)
输出：
r*a*j*a
代码检查每个索引并打印输出。
name1 = input("Enter the first name: ") name2 = input("Enter the second name: ") name3 = input("Enter the third name: ") name4 = input("Enter the fourth name: ") name = [name1, name2, name3, name4] for letter in name: if letter[0]=='G': print(letter) else: continue for alphabet in name: if alphabet[-1]=='a': print(alphabet) else: continue for alpha in name: for i in alpha: if i==' ': print(alpha) else: continue for character in name: if len(character)>9: print(character) else: continue output: Enter the first name: Guhanraja Enter the second name: Lakshmi Pritha Enter the third name: Guru Prasanna Enter the fourth name: Varatharajan Guhanraja Guru Prasanna Guhanraja Lakshmi Pritha Guru Prasanna Lakshmi Pritha Guru Prasanna Lakshmi Pritha Guru Prasanna Varatharajan
