Python中的判断、循环 if...else，while

if...else语句：

a=3; b=3; 
if a == b :
print(a,b)
elif a <= b :
print(str(a) + " is less than " + str(b))
else :
print(str(a) + " is greater than " + str(b))

###################################

n = 3
if (n >= 0 and n <= 8) or (n >= 12 and n <= 25): 
print("hhh")

##或者 

n = 3
if (n >= 0 and n <= 8) or (n >= 12 and n <= 25): print("hhh")

 

一个字符串也相当于是一个数组，通过for循环可以将每个字符输出

for循环，相当于foreach
c="cc";d="dd";e="ee";f="ff"
pa = [c,d,e,f]
for p in pa:
print("current p is:",p)

使用下标索引：
c="cc";d="dd";e="ee";f="ff"
pa = [c,d,e,f]
for index in range(len(pa)):
print("current p is:",pa[index])

或者：
c="cc";d="dd";e="ee";f="ff"
pa = [c,d,e,f]
for index in range(2,4):
print("current p is:",pa[index])

使用while循环：
c="cc";d="dd";e="ee";f="ff"
pa = [c,d,e,f]
i=0
while(i<len(pa)):
print("current p is:",pa[i])
i=i+1

while 语句时还有另外两个重要的命令 continue，break 来跳过循环，continue 用于跳过该次循环，break 则是用于退出循环

转载于:https://www.cnblogs.com/dreamer-fish/p/3818408.html