python和C语言混合编程实例

        return Py_BuildValue("d", -3.0);        /* convert C -> Python */
    }
    fd_set read, write;
    FD_ZERO(&read);
    FD_ZERO(&write);

    FD_SET(fd, &read);
    FD_SET(fd, &write);

    if (select(fd + 1, &read, &write, NULL, &tv) == 0) {
        close(fd);
        return Py_BuildValue("d", -4.0);        /* convert C -> Python */
    }

    double etime = mytime();
    time = etime - stime;
    if (!FD_ISSET(fd, &read) && !FD_ISSET(fd, &write)) {
        close(fd);
        return Py_BuildValue("d", -4.0);        /* convert C -> Python */
    }
    close(fd);
    return Py_BuildValue("d", time/1000);        /* convert C -> Python */
}

/* registration table  */
static struct PyMethodDef portping_methods[] = {
    {"tcpping", tcpping, METH_VARARGS},       /* method name, C func ptr, always-tuple */
    {NULL, NULL}                   /* end of table marker */
};

/* module initializer */
void inittcpportping( )                       /* called on first import */
{                                      /* name matters if loaded dynamically */
    (void) Py_InitModule("tcpportping", portping_methods);   /* mod name, table ptr */
}

编译成python模块
gcc tcpportping.c  -I/usr/include/python2.4 -shared -L/usr/bin -fpic -lpython2.4 -o tcpportping.so

下面是python调用c模块的代码：
#!/usr/bin/env python

import tcpportping
import time

i = 0
while i < 5:
    t = tcpportping.tcpping('www.baidu.com', 80, 1000)
    if t < 0:
        print "time out"
    else:
        print t
    time.sleep(0.5)
    i += 1
执行python代码就可以实现端口ping的结果，从测试的情况来看，该程序执行的结果跟普通的ping几乎没有什么差别。