链接OpenCV静态库相关错误

问题1

以前都是用***.so动态库，这次换成了***.a静态库，就用了一个opencv读图的功能，make的时候报这样的错误：

./opencv3.4.13/lib/libopencv_core.a(persistence_c.cpp.obj): In function `cvOpenFileStorage_(CvFileStorage*&, char const*, CvMemStorage*, int, char const*)':
persistence_c.cpp:(.text._ZL18cvOpenFileStorage_RP13CvFileStoragePKcP12CvMemStorageiS3_+0xa0c): undefined reference to `gzopen'
./opencv3.4.13/lib/libopencv_core.a(persistence.cpp.obj): In function `icvPuts(CvFileStorage*, char const*)':
persistence.cpp:(.text._Z7icvPutsP13CvFileStoragePKc+0x1ac): undefined reference to `gzputs'
./opencv3.4.13/lib/libopencv_core.a(persistence.cpp.obj): In function `icvGets(CvFileStorage*, char*, int)':
persistence.cpp:(.text._Z7icvGetsP13CvFileStoragePci+0x180): undefined reference to `gzgets'
./opencv3.4.13/lib/libopencv_core.a(persistence.cpp.obj): In function `icvEof(CvFileStorage*)':
persistence.cpp:(.text._Z6icvEofP13CvFileStorage+0x28): undefined reference to `gzeof'
./opencv3.4.13/lib/libopencv_core.a(persistence.cpp.obj): In function `icvCloseFile(CvFileStorage*)':
persistence.cpp:(.text._Z12icvCloseFileP13CvFileStorage+0x18): undefined reference to `gzclose'
./opencv3.4.13/lib/libopencv_core.a(persistence.cpp.obj): In function `icvRewind(CvFileStorage*)':
persistence.cpp:(.text._Z9icvRewindP13CvFileStorage+0x18): undefined reference to `gzrewind'
./opencv3.4.13/lib/libopencv_core.a(persistence.cpp.obj): In function `icvFSFlush(CvFileStorage*)':
persistence.cpp:(.text._Z10icvFSFlushP13CvFileStorage+0x158): undefined reference to `gzputs'
./opencv3.4.13/lib/libopencv_core.a(persistence.cpp.obj): In function `icvClose(CvFileStorage*, cv::String*)':
persistence.cpp:(.text._Z8icvCloseP13CvFileStoragePN2cv6StringE+0xb0): undefined reference to `gzclose'

发现gzopen,gzclose,gzputs都是zlib里面的函数，libopencv_core.a用到了zlib里边的一些功能，看来是要要链接zlib库，然而编译的时候没找到这个库，现在来安装zlib然后加上去。

zlib在opencv的3rdparty里面有，编译OpenCV的时候勾上它：

编译成功后在对应了路径就会有：

得到libzlib.a后，在Makeflie里面链接库的地方加上-lzlib。
重要的是，要注意顺序，加在-lopencv_core后面。（静态库的顺序是有影响的）

大概像这样写：

gcc main.c -lopencv_core -lzlib -o main

---

问题2

error while loading shared libraries: ../../lib/libopencv_core.so: cannot open shared object file: No such file or directory

用下面的命令查看信息：

readelf -d libopencv_highgui.so

Dynamic section at offset 0x50580 contains 30 entries:
  Tag Type Name/Value
 0x00000001 (NEEDED) Shared library: [../../lib/libopencv_core.so]
 0x00000001 (NEEDED) Shared library: [../../lib/libopencv_imgproc.so]
 0x00000001 (NEEDED) Shared library: [libstdc++.so.6]
 0x00000001 (NEEDED) Shared library: [libm.so.6]
 0x00000001 (NEEDED) Shared library: [libgcc_s.so.1]
 0x00000001 (NEEDED) Shared library: [libc.so.6]
 0x0000000c (INIT) 0xa410
 0x0000000d (FINI) 0x49ed4
 0x00000019 (INIT_ARRAY) 0x50000
 0x0000001b (INIT_ARRAYSZ) 12 (bytes)
 0x0000001a (FINI_ARRAY) 0x5000c
......

发现它找的是相对路径../../lib/libopencv_core.so

参考：
https://www.codenong.com/cs106665290/
http://blog.chinaunix.net/uid-27134408-id-5122776.html

出现问题的原因是因为配置cmake时填写的时arm-linux,应该填写Linux，进行重新配置编译生成库就行了