Day3: Python基础：字符串操做

1、字符串切片，从左至右0～value

i = 'ABCDEFSHJIKLMN'

S1 = i[0]
S2 = i[2]
S3 = i[5:10]

print(S1,S2,S3)
A C FSHJI    /***顾头不顾尾***/

2、字符串切片，从右至左-1～value

i = 'ABCDEFSHJIKLMN'

# S1 = i[0]
# S2 = i[2]
# S3 = i[5:10]
#
# print(S1,S2,S3)
S4 = i[-1]
S1 = i[0:-1]
S2 = i[:]
S3 = i[0:]

N
ABCDEFSHJIKLM
ABCDEFSHJIKLMN
ABCDEFSHJIKLMN

3、按步长取值，步长为1：取每个值；步长为2：是隔一个取一个值

i = 'ABCDEFSHJIKLMN'
S1 = i[0:5:2]
S2 = i[0:5:1]
print(S1)
print(S2)

 

i = 'ABCDEFSHJIKLMN'
S1 = i[5:0:-2]
S2 = i[10:5:-3]
print(S1)
print(S2)

FDB
KH

4、倒着取

i = 'ABCDEFSHJIKLMN'
S1 = i[-1:]
S2 = i[8:2:-2]
S3 = i[-1::-1]
print(S1)
print(S2)
print(S3)

N
JSE
NMLKIJHSFEDCBA

 5、作业：任意输入两个数，计算两个数如（5+100或5 +        100等）的和

context = input('请输入你要计算的加数，格式：n + n:')

S = context.strip(' ')
I = S.split('+')
sum = 0
for Loop in I:
    sum = sum + int(Loop)
print(int(sum))

 6、作业：第二种方法：任意输入两个数，计算两个数如（5+100或5 +        100等）的和

context = input('请输入你要计算的加数，格式：n + n:')
S = context.strip()
I = S.index('+')
num1 = int(S[0:I])
num2 = int(S[I+1:])
print(num1)
print(num2)
print(num1 + num2)

  7、任意输入一串字母与数字的组合，计算数字的和

#任意输入一串字母与数字的组合，计算数字的和
sum = 0
context = input('请任意输入一串字母与数字的组合：').strip()
for i in context:
    if i.isdigit() == 1:
        sum = sum + int(i)
print(sum)

  8、字符串IS判断S = '12345678990'S1 = 'ABCDqwer'

S3 = 'asfbasfdcdasd11234'


print(S.isdigit())      判断字符串是否只有数字组成，返回True或False
print(S1.isalpha())     判断字符串是否只有字母组成，返回True或False
print(S3.isalnum())     判断字符串是否只有字母和数字组成，返回True或False

print(S3.isdigit())
print(S3.isalpha()) 
print(S3.isalnum())