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https://github.com/laserpants/dotenv-cpp
:cow: A utility to load environment variables from a .env file
https://github.com/laserpants/dotenv-cpp
cpp dotenv dotenv-cpp header-only
Last synced: about 1 month ago
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:cow: A utility to load environment variables from a .env file
- Host: GitHub
- URL: https://github.com/laserpants/dotenv-cpp
- Owner: laserpants
- License: bsd-3-clause
- Created: 2018-09-08T19:32:04.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2023-06-29T20:00:04.000Z (over 1 year ago)
- Last Synced: 2023-06-29T21:22:00.067Z (over 1 year ago)
- Topics: cpp, dotenv, dotenv-cpp, header-only
- Language: C++
- Homepage:
- Size: 80.1 KB
- Stars: 19
- Watchers: 2
- Forks: 10
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# dotenv-cpp
## Installation
The library is header-only, so there is nothing to build. You could simply merge the `include` directory into your project root, entering something like
```bash
mkdir -p include
cp -rn /dotenv-cpp/include/ .
```
and compile, adding `-I include/laserpants/dotenv` to your build command, which then allows you to `#include "dotenv.h"`.
Although the above method is sufficient for many use cases; for proper CMake support, you should install the library using a sequence of command such as
```bash
cd
mkdir -p build
cd build
cmake ..
make
sudo make install
```
By default, the headers will then be installed to `include/laserpants/dotenv-/`, relative to the CMake install prefix (`/usr/local/` on Linux/Unix). To compile *without* CMake, you can then use a flag
```
-I /usr/local/include/laserpants/dotenv-
```
or the equivalent path on other platforms.
For CMake-based projects, your project's `CMakeLists.txt` file could look something like the following:
```cmake
cmake_minimum_required(VERSION 3.2)
project(test)
find_package(laserpants_dotenv)
add_executable(example example.cpp)
target_link_libraries(example laserpants::dotenv)
```
Then, in `example.cpp`, just
```cpp
#include
```
## Usage
### Example
Given a file `.env`
```shell
DATABASE_HOST=localhost
DATABASE_USERNAME=user
DATABASE_PASSWORD="antipasto"
```
and a program `example.cpp`
```cpp
// example.cpp
#include
#include
int main()
{
dotenv::init();
std::cout << std::getenv("DATABASE_USERNAME") << std::endl;
std::cout << std::getenv("DATABASE_PASSWORD") << std::endl;
return 0;
}
```
the output is:
```
user
antipasto
```
### Default values
`dotenv::getenv()` is a wrapper for `std::getenv()` that also takes a default value, in case the variable is empty:
```cpp
std::cout << dotenv::getenv("DATABASE_USERNAME", "anonymous") << std::endl;
```
### Referencing other variables
Other variables can be referenced using either `${VARIABLE}` or `$VARIABLE`.
#### Example:
Given this program
```cpp
#include
#include
#include "dotenv.h"
int main(int argc, char **argv)
{
dotenv::init("resolve.env");
std::cout << std::getenv("MESSAGE") << std::endl;
return 0;
}
```
and this `resolve.env`
```
TEMPERATURE = cold
EXTENT = " long "
SEASON = '$EXTENT $TEMPERATURE winter'
MORE = and $TEMPERATURE ice
CONTAINS = lots of ${TEMPERATURE} snow $MORE
MESSAGE = I wish you a ${SEASON}, with $CONTAINS
```
the output becomes
```
I wish you a long cold winter, with lots of cold snow and cold ice
```
### Options
By default, if a name is already present in the environment, `dotenv::init()` will replace it with the new value. To preserve existing variables, you must pass the `Preserve` flag.
```cpp
dotenv::init(dotenv::Preserve);
std::cout << std::getenv("DATABASE_USERNAME") << std::endl;
std::cout << std::getenv("DATABASE_PASSWORD") << std::endl;
```
Updating the previous example, recompiling and running the program again, after setting the `DATABASE_USERNAME` variable, e.g. as
```
DATABASE_USERNAME=root ./example
```
the output this time is:
```
root
antipasto
```
## Changelog
### 0.9.3
#### Added
- Add cctype header needed by std::isspace
### 0.9.2
#### Added
- Add support for referencing other variables in variable definitions
### 0.9.1
#### Added
- Add wrapper for setenv to support MSVC
### 0.9.0
- Initial version