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非递归的方法:
def trim(s):
while(s[:1]==' '):
s=s[1:]
while(s[-1:]==' '):
s=s[:-1]
return s
递归的方法:
def trim(s):
if len(s)==0:
return s
elif s[:1]==' ':
return trim(s[1:])
elif s[-1:]==' ':
return trim(s[:-1])
return s
# 测试:
if trim('hello ') != 'hello':
print('测试失败!')
elif trim(' hello') != 'hello':
print('测试失败!')
elif trim(' hello ') != 'hello':
print('测试失败!')
elif trim(' hello world ') != 'hello world':
print('测试失败!')
elif trim('') != '':
print('测试失败!')
elif trim(' ') != '':
print('测试失败!')
else:
print('测试成功!')