php调用C程序
树莓派2，开发nginx + php + sqlite，现在php和C语言的程序都写好了，C程序写的是串口通信，但是用exec调用返回是空，但是如果调用helloworld却可以调用，请问这是为什么？
回复讨论(解决方案)
php 的 exec 接受的是外部程序的标准输出
那应该用什么调用呢，system，exec，passthru都不行，本人初写，求教
关键是你的 c 程序是如何向 php 返回数据的
关键是你的 c 程序是如何向 php 返回数据的
我C程序是串口发指定信息，返回信息写入sqlite的数据库，然后php查询数据库
问题知道了，是php调用C程序时，串口打开失败，但单独运行C程序是可以的，不知道为什么
那exec调用返回是不是空有什么关系？
你查表得数据不就行了？
那exec调用返回是不是空有什么关系？
你查表得数据不就行了？
现在是串口不能open，nFd = open("/dev/ttyAMA0", O_RDWR|O_NOCTTY);这个返回-1,。
你那是 c 的问题，不是 php 的问题
你得去 c/c++ 找专家
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