subprocess.Popen(...)

python3 实现代码： 备注write 要使用bytes 在最后结果转为str 显示时才不会出现 b'' 这样的字节显示

import subprocess

obj = subprocess.Popen(["python3"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
obj.stdin.write(bytes('print(1)',encoding='utf-8'))
# obj.stdin.write('print 2 \n ')
# obj.stdin.write('print 3 \n ')
# obj.stdin.write('print 4 \n ')
obj.stdin.close()

cmd_out = obj.stdout.read()
obj.stdout.close()
cmd_error = obj.stderr.read()
obj.stderr.close()

print(str(cmd_out,encoding='utf-8'))
print(cmd_error)

异常处理：
备注：python3 中 
try:

except Exception as e :

______________________________________________________________

while True:
    num1 = input('num1')
    num2 = input("num2")
    try:
         num1 = int(num1)
         num2 = int(num2)
         result = num1 + num2
    except Exception as e :
        print("出现异常，信息如下：")
        print(e)

其他异常

try:

    # 主代码块

    pass

except KeyError,e:

    # 异常时，执行该块

    pass

else:

    # 主代码块执行完，执行该块

    pass

finally:

    # 无论异常与否，最终执行该块

    pass

主动异常和断言

while True:

    num1 = input('num1')

    num2 = input("num2")

    try:

         num1 = int(num1)

         raise Exception('错误了。。。')  #主动异常

         num2 = int(num2)

         assert 1 ==1           #断言

         result = num1 + num2

         print(result)

    except Exception as e :

        print("出现异常，信息如下：")

        print(e)