0.（ubuntu 20.4 LTS版本）

1.源程序

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <unistd.h>

#include <libusb-1.0/libusb.h>

#include <stdio.h>

#include <sys/types.h>

 

static void print_devs(libusb_device **devs)

{

	libusb_device *dev;

	int i = 0;

 

	while ((dev = devs[i++]) != NULL) {

		struct libusb_device_descriptor desc;

		int r = libusb_get_device_descriptor(dev, &desc);

		if (r < 0) {

			fprintf(stderr, "failed to get device descriptor");

			return;

		}

 

		printf("%04x:%04x (bus %d, device %d)\n",

			desc.idVendor, desc.idProduct,

			libusb_get_bus_number(dev), libusb_get_device_address(dev));

	}

}

 

int main(void)

{

	libusb_device **devs;

	int r;

	ssize_t cnt;

 

	r = libusb_init(NULL);

	if (r < 0)

		return r;

 

	cnt = libusb_get_device_list(NULL, &devs);

	if (cnt < 0)

		return (int) cnt;

 

	print_devs(devs);

	libusb_free_device_list(devs, 1);

 

	libusb_exit(NULL);

	return 0;

}

2.编译错误信息

/usr/bin/ld: ./main.o: in function `print_devs':
main.c:(.text+0x3b): undefined reference to `libusb_get_device_descriptor'
/usr/bin/ld: main.c:(.text+0x72): undefined reference to `libusb_get_device_address'
/usr/bin/ld: main.c:(.text+0x81): undefined reference to `libusb_get_bus_number'
/usr/bin/ld: ./main.o: in function `main':
main.c:(.text+0x114): undefined reference to `libusb_init'
/usr/bin/ld: main.c:(.text+0x133): undefined reference to `libusb_get_device_list'
/usr/bin/ld: main.c:(.text+0x161): undefined reference to `libusb_free_device_list'
/usr/bin/ld: main.c:(.text+0x16b): undefined reference to `libusb_exit'
collect2: error: ld returned 1 exit status

3.链接的h文件 main.d文件我看了 libusb.h的库确实包含进去了但还是报undefined

./main.o: main.c /usr/include/stdc-predef.h /usr/include/stdio.h \
 /usr/include/x86_64-linux-gnu/bits/libc-header-start.h \
 /usr/include/features.h /usr/include/x86_64-linux-gnu/sys/cdefs.h \
 /usr/include/x86_64-linux-gnu/bits/wordsize.h \
 /usr/include/x86_64-linux-gnu/bits/long-double.h \
 /usr/include/x86_64-linux-gnu/gnu/stubs.h \
 /usr/include/x86_64-linux-gnu/gnu/stubs-64.h \
 /usr/lib/gcc/x86_64-linux-gnu/9/include/stddef.h \
 /usr/lib/gcc/x86_64-linux-gnu/9/include/stdarg.h \
 /usr/include/x86_64-linux-gnu/bits/types.h \
 /usr/include/x86_64-linux-gnu/bits/timesize.h \
 /usr/include/x86_64-linux-gnu/bits/typesizes.h \
 /usr/include/x86_64-linux-gnu/bits/time64.h \
 /usr/include/x86_64-linux-gnu/bits/types/__fpos_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/__mbstate_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/__fpos64_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/__FILE.h \
 /usr/include/x86_64-linux-gnu/bits/types/FILE.h \
 /usr/include/x86_64-linux-gnu/bits/types/struct_FILE.h \
 /usr/include/x86_64-linux-gnu/bits/stdio_lim.h \
 /usr/include/x86_64-linux-gnu/bits/sys_errlist.h /usr/include/string.h \
 /usr/include/x86_64-linux-gnu/bits/types/locale_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/__locale_t.h \
 /usr/include/strings.h /usr/include/stdlib.h \
 /usr/include/x86_64-linux-gnu/bits/waitflags.h \
 /usr/include/x86_64-linux-gnu/bits/waitstatus.h \
 /usr/include/x86_64-linux-gnu/bits/floatn.h \
 /usr/include/x86_64-linux-gnu/bits/floatn-common.h \
 /usr/include/x86_64-linux-gnu/sys/types.h \
 /usr/include/x86_64-linux-gnu/bits/types/clock_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/clockid_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/time_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/timer_t.h \
 /usr/include/x86_64-linux-gnu/bits/stdint-intn.h /usr/include/endian.h \
 /usr/include/x86_64-linux-gnu/bits/endian.h \
 /usr/include/x86_64-linux-gnu/bits/endianness.h \
 /usr/include/x86_64-linux-gnu/bits/byteswap.h \
 /usr/include/x86_64-linux-gnu/bits/uintn-identity.h \
 /usr/include/x86_64-linux-gnu/sys/select.h \
 /usr/include/x86_64-linux-gnu/bits/select.h \
 /usr/include/x86_64-linux-gnu/bits/types/sigset_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/__sigset_t.h \
 /usr/include/x86_64-linux-gnu/bits/types/struct_timeval.h \
 /usr/include/x86_64-linux-gnu/bits/types/struct_timespec.h \
 /usr/include/x86_64-linux-gnu/bits/pthreadtypes.h \
 /usr/include/x86_64-linux-gnu/bits/thread-shared-types.h \
 /usr/include/x86_64-linux-gnu/bits/pthreadtypes-arch.h \
 /usr/include/x86_64-linux-gnu/bits/struct_mutex.h \
 /usr/include/x86_64-linux-gnu/bits/struct_rwlock.h /usr/include/alloca.h \
 /usr/include/x86_64-linux-gnu/bits/stdlib-float.h /usr/include/unistd.h \
 /usr/include/x86_64-linux-gnu/bits/posix_opt.h \
 /usr/include/x86_64-linux-gnu/bits/environments.h \
 /usr/include/x86_64-linux-gnu/bits/confname.h \
 /usr/include/x86_64-linux-gnu/bits/getopt_posix.h \
 /usr/include/x86_64-linux-gnu/bits/getopt_core.h \
 /usr/include/x86_64-linux-gnu/bits/unistd_ext.h \
 /usr/include/libusb-1.0/libusb.h \
 /usr/lib/gcc/x86_64-linux-gnu/9/include/stdint.h /usr/include/stdint.h \
 /usr/include/x86_64-linux-gnu/bits/wchar.h \
 /usr/include/x86_64-linux-gnu/bits/stdint-uintn.h \
 /usr/include/x86_64-linux-gnu/sys/time.h /usr/include/time.h \
 /usr/include/x86_64-linux-gnu/bits/time.h \
 /usr/include/x86_64-linux-gnu/bits/types/struct_tm.h \
 /usr/include/x86_64-linux-gnu/bits/types/struct_itimerspec.h \
 /usr/lib/gcc/x86_64-linux-gnu/9/include/limits.h \
 /usr/lib/gcc/x86_64-linux-gnu/9/include/syslimits.h \
 /usr/include/limits.h /usr/include/x86_64-linux-gnu/bits/posix1_lim.h \
 /usr/include/x86_64-linux-gnu/bits/local_lim.h \
 /usr/include/linux/limits.h \
 /usr/include/x86_64-linux-gnu/bits/posix2_lim.h

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