与libbluetooth.so连接

Question

在Ubuntu14.04上，我尝试做一个蓝牙设备清单的小例子，但是在编译这个极简的演示http://people.csail.mit.edu/albert/bluez-intro/c404.html时，我面临一个简单的问题，就是如何链接到蓝牙共享库

$ sudo apt-get install libbluetooth-dev

$ gcc -lbluetooth simplescan.c -o simplescan
/tmp/ccuwRsB5.o: In function `main':
simplescan.c:(.text+0x79): undefined reference to `hci_get_route'
simplescan.c:(.text+0x8c): undefined reference to `hci_open_dev'
simplescan.c:(.text+0x132): undefined reference to `hci_inquiry'
simplescan.c:(.text+0x18f): undefined reference to `ba2str'
simplescan.c:(.text+0x1f0): undefined reference to `hci_read_remote_name'
collect2: error: ld returned 1 exit status

$ nm -D /usr/lib/x86_64-linux-gnu/libbluetooth.so.3.13.0 | grep hci_get_route
0000000000008f00 T hci_get_route

似乎找到了蓝牙共享库并包含了所需的功能，但是链接阶段没有实现。

Answer 1

解决办法(对我来说)是令人惊讶的:给gcc的论点的顺序很重要。"-lbluetooth“应放在”simplescan.c“之后：

$ gcc simplescan.c -lbluetooth -o simplescan # Success
$ gcc -lbluetooth simplescan.c -o simplescan # Failure
/tmp/ccWhZFXs.o: In function `main':
simplescan.c:(.text+0x79): undefined reference to `hci_get_route'
simplescan.c:(.text+0x8c): undefined reference to `hci_open_dev'
simplescan.c:(.text+0x132): undefined reference to `hci_inquiry'
simplescan.c:(.text+0x18f): undefined reference to `ba2str'
simplescan.c:(.text+0x1f0): undefined reference to `hci_read_remote_name'
collect2: error: ld returned 1 exit status