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# a complete C rest client demo project

## project structure

- base64.c/base64.h: a util for base64.encode/decode

- main.c: call the rest api for IoTDB

## How to build

dependency: libcurl

- example: Ubuntu 16.04 STL (Ubuntu 20.04 may have some problems)

```shell script
sudo apt-get install libcurl4-openssl-dev
```

Before build, you must install the libcurl.

build steps:

```shell script
mkdir build
cd build
cmake ..
make 
```

Eventually, you will get an executable program `c_rest_iotdb` in `build` directory.

## cross compilation

- os : Ubuntu 16.04 STL

1. choose and install cross compiler according to the target host

arm-linux-gnueabihf-gcc as an example.

- arm-linux-gnueabihf-gcc

```shell script
sudo apt-get install gcc-arm-linux-gnueabihf
```

2. cross compile libcurl

- download the *.tar.gz in https://curl.haxx.se/download/, and uncompress it.

- compile and install

```shell script
./configure --host=arm-linux/arm-linux-gnueabihf/others CC=arm-linux-gnueabihf-gcc --prefix=`install dir` --enable-static --with-wolfssl
make
make install
```

3. cross compile the example program

```shell script
arm-linux-gnueabihf-gcc main.c base64.c -o c_rest -L `(libcurl install dir)/lib/` -l curl
```

if can't find `curl/curl.h`, you can just simply change to the absolutely path or specify the include path.

Reference Materials

libcurl usage:

https://blog.csdn.net/myvest/article/details/82899788

compilation:

https://blog.csdn.net/u011641885/article/details/46900771

https://www.cnblogs.com/flyinggod/p/10148228.html

https://blog.csdn.net/fangye945a/article/details/86500817

https://www.cnblogs.com/yxh-l-0824/p/13254891.html

https://www.cnblogs.com/tansuoxinweilai/p/11602830.html

https://www.cnblogs.com/pied/p/8805883.html