python中的循环语法使用指南

# 打印五次我爱python
i = 0  # 计数器
while i < 5:
    print('我爱python!')
    i += 1  # 计数器需要不断变化，否则也会陷入死循环

# 计算1-100 的和
i = 1
sum = 0  # sum 存放1-100的和
while i <= 100:
    sum += i
    i += 1
print(sum)

# 计算1-100 之间3的倍数的和
i = 1
sum = 0
while i <= 100:
    if i % 3 == 0:
        sum += i
    i += 1
print(sum)

i = 1
while i <= 10:
    if i == 5:  # 当i==5时跳出循环
        break
    print(i)
    i += 1
print('代码块1')

i = 1
while i <= 10:
    if i == 5:
        i += 1  # 这里一定要改变计数器，否则会陷入死循环
        continue
    print(i)
    i += 1

i = 1
while i <= 10:
    if i == 5:
        continue  # 当i==5的时候，循环体后面的代码都不会执行，所以i一直等于5，陷入死循环
    print(i)
    i += 1

i = 1
while i < 5:  # 控制行数
    j = 1
    while j <= i:  # 控制列数
        print(j,end=' ')
        j += 1
    print()  # 换行
    i += 1

i = 1
while i <= 9:
    j = 1
    while j <= i:
        print(f'{i} * {j} = {i * j}',end='\t')
        j += 1
    print()
    i += 1

message = 'abcdef'
for ch in message:
    print(ch)

message = 'abcdef'
for ch in message:
    if ch == 'd':
        break;
    print(ch)

message = 'abcdef'
for ch in message:
    if ch == 'd':
        continue
    print(ch)

i = 1
while i <= 5:
    if i == 3:
        break
    print(i)
    i += 1
else:
    print('循环正常结束')

i = 1
while i <= 5:
    if i == 3:
        i += 1
        continue
    print(i)
    i += 1
else:
    print('循环正常结束')