python温度转换

#TempConvert.py
TempStr = input('请输入带有符号的温度值:')
if TempStr[-1] in ['F', 'f']:
    C = (eval(TempStr[0:-1]) - 32)/1.8
    print('转换后的温度是{:.2f}C'.format(C))
elif TempStr[-1] in ['C','c']:
    F = 1.8*eval(TempStr[0:-1]) + 32
    print('转换后的温度是{:.2f}F'.format(F))
else:
    print('输入格式错误')