python中的字符转运算符、字符串处理方式_python

def CalSingleVals(val1, val2):
    op = ['+', '-', '*', '/']
    rtValList = []
 
    for op1 in op:
        st = str(val1) + op1 + str(val2)
        result = int(eval(st))

def trim(s):
...     import re
...     if s.startswith(' ') or s.endswith(' '):
...         return re.sub(r"^(\s+)|(\s+)$", "", s)
...     return s

s1 = 'hello'
s2 = 'world'
print(s1+s2)

s1 = 'a' * 5
print(s1)

s1 = 'hello world!'
result = 'w' in s1
print(result)

s1 = 'hello world!'
result = 'w' not in s1
print(result)

s1 = 'hello world!'
s2 = 'hello world!'
result = s1 is s2
print(result)

s1 = 'hello world!'
s2 = 'hello world!'
result = s1 is not s2
print(result)

s1 = 'hello world!'
s2 = 'hello world!'
result = s1 == s2
print(result)

s1 = 'hello world!'
s2 = 'hello world!'
result = s1 != s2
print(result)