表达式if ... else
>>> if 3 > 4: ... print('False') ... else: ... print('True') ... True
表达式if ... elif...else
>>> a = 10 >>> if a > 15: ... print("ok") ... elif a < 15: ... print("good") ... else: ... print("what") ... good
循环while
while True: ... a = input('>>>').strip() ... b = 10 ... c = int(a) ... if c > b: ... print('go on') ... continue ... else: ... print('ok') ... break
循环for loop
>>> for i in range(10): ... print('loop:',i) ... loop: 0 loop: 1 loop: 2 loop: 3 loop: 4 loop: 5 loop: 6 loop: 7 loop: 8 loop: 9
>>> for i in range(10): ... if i >8: ... break ... print('loop:',i) ... loop: 0 loop: 1 loop: 2 loop: 3 loop: 4 loop: 5 loop: 6 loop: 7 loop: 8
代码优化
a = 2 b = 3 if a > b: c = a + b else: c = a - b print(c) # 优化后代码量减少 a = 4 b = 5 c = a + b if a > b else a - b print(c)
pass 、continue 和 break
# pass 跳过,本次没操作 for i in range(10): if i == 5: pass else: print('loop', i)
# continue 跳出本次循环,继续下次循环 for i in range(10): if i == 5: continue print('loop', i)
# break 跳出当前循环 for i in range(10): if i == 5: for j in range(10): print('in loop', j) if j == 6: break continue print('out loop', i)