1、 了解系統調用fork()、execl()、exit()、getpid()和waitpid()的功能和實現過程
2、 編寫一段程序實現以下功能：
a) 使用系統調用fork()創建兩個子進程
b) 父進程重復顯示字符串”parent:”，并使用函數getpid()顯示自己的進程ID。
c) 兩個子進程分別重復顯示字符串”child:”，并使用函數getpid()顯示自己的進程ID
3、 編寫一段程序實現以下功能：
a) 使用系統調用fork()創建一個子進程
b) 子進程顯示自己的進程ID和字符串": The child is Calling an exec.\n"，然后通過execl()調用系統命令ps顯示當前運行的進程情況，從而更換自己的執行代碼，最后調用exit()結束。
c) 父進程顯示自己的進程ID和字符串” ": The parent is waiting for child to exit.\n "，然后調用waitpid()等待子進程結束，并在子進程結束后顯示”The parent exit.\n
With OpenSSL 0.9.6, a new component has been added to support external crypto devices, for example accelerator cards. The component is called ENGINE, and has still a pretty experimental status and almost no documentation. It s designed to be fairly easily extensible by the Calling programs.
As science advances, novel experiments are becoming more and more complex, requiring a zoo of control devices and electronics executing complicated sequences of steps. Device availability and monetary constrains usually lead to a highly heterogeneous setup with components from several different manufacturers using many different protocols and interfacing mechanisms. This often results in control software being puzzled together to use and provide a multitude of interfacing and control functionality, each using their own Calling conventions, data structures, etc. To make matters worse, usually a group of relatively independent programmers is trying to write and maintain the code base. Often this causes extensive duplication of effort as program segments are hard to reuse, since unpredictable changes to the segments by the original authors might compromise other code using these segments.
This function checks the mailbox to see if a message is available. Unlike OSMboxPend(),
OSMboxAccept() does not suspend the Calling task if a message is not available.
GPS 接收程序 DEMO。
HsGpsDll Library 1.1
A GPS Control/Component for C/C++
HsGpsDll is a Windows Dynamic Link Library which provides access to any NMEA-183 compliant GPS receiver via a serial communications port. HsGpsDll is designed for use from Visual C, Visual Basic or other languages, capable of Calling DLL functions. HsGpsDll allows a user application to read from a GPS device the current GPS position fix, velocity over ground (speed in kilometers per hour), plus number of of sattelites in view, current altitude (against mean sea level) and UTC date and time
