from functools import reduce

def str2num(s):
    return int(s)

def calc(exp):
    ss = exp.split('+')
    ns = map(str2num, ss)
    return reduce(lambda  acc, x: acc+x, ns)

def main():
    r = calc('100+200+345')
    print('100+200+345=', r)
    r =calc('99+88+7.6')
    print('99+99+7.6=', r)

main()
print('END')

# 运行结果：
100+200+345= 645
Traceback (most recent call last):
  File "/Users/pengchen/workspace/pythonProject1/错误、调试和测试/错误处理.py", line 17, in <module>
    main()
  File "/Users/pengchen/workspace/pythonProject1/错误、调试和测试/错误处理.py", line 14, in main
    r =calc('99+88+7.6')
  File "/Users/pengchen/workspace/pythonProject1/错误、调试和测试/错误处理.py", line 9, in calc
    return reduce(lambda  acc, x: acc+x, ns)
  File "/Users/pengchen/workspace/pythonProject1/错误、调试和测试/错误处理.py", line 4, in str2num
    return int(s)
ValueError: invalid literal for int() with base 10: '7.6'