循环结构

while循环

流程图：

语法格式：
while 条件语句：
循环体

示例代码

num=1
sum=0
while  num<10:
    sum = sum+num
    print(sum)
    num +=1

un_users  = ['alice','brian','candace']
co_users=[]
while un_users:
    cur_user = un_users.pop()
    print("Verifying user:" + cur_user.title())
    co_users.append(cur_user)

while co_users:
    user = co_users.pop()
    print(user,end='  ') #不换行输出

break continue

break语句立即退出while循环，跳出循环体
continue跳过本轮循环，执行下一轮循环

num=1;
while num<10:
    if num==5:
       break
    print(num , end='   ')
    num+=1

print()
x=0
while x<10:
    x+=1
    if  x%2==0 :
        continue
    print(x,end = '  ')

输出结果：

for循环

for循环需要用到range()函数。
range()函数的作用是生成整数序列，由三个参数决定序列的大小和范围：起始值，终值和步长。是半开区间，不包括序列的终值。

实例代码

a = 'Hello Myworld'
for i in a:
    print(i,end="   ")
print()
for j in range(10):
    print(j,end="  ")
print()
sum=0
for x in [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]:
    sum += x
    if x==15:
        print(x,end="  =  ")
        print(sum)
    else:
        print(x,end="  +  ")
for y in range(1,20,3):
    print(y,end="   ")

实现冒泡排序 嵌套

a = [1,55,22,11,44,66,6666,23,56,87,45,5]
for i in range(0,12):
    for j in range(i,12):
        if a[i] >a[j]:
            temp=a[i]
            a[i] = a[j]
            a[j] = temp
for k in range(0,12):
    print(a[k],end = "   ")