Practical library series : Configuration File
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日本語版はこちら： 実用ライブラリシリーズ：設定ファイル
Overview
Some applications need variable configurations.
For example, The configuration of account information for Twitter...
It's not good for publish if I implemented a program with a account information for Twitter, and it's not secure.
So, in this document we will show you a configuration file helper class for local file system on mbed.
You can use a variable configuration with it.
Basic concept
Features
- Available 'Key' and the 'Value' configuration set.
- Supported read and write.
- You can write comments in a configuration file. The library will ignore the comments.
Library
Class structure
The class is only
ConfigFile
in this library.
Projects
The library project is ConfigFile. And the test program is ConfigFile_TestProgram.
The library project ConfigFile hasn't mbed library in the project. So you can import the link of the library.
You can run the test program ConfigFile_TestProgram if you want to check the functions.
How to use it?
Configuration file
We need a configuration file.
- A comment line started by #.
- Empty lines have not meaning.
- Key=Value based configuration.
- A space character in a side of a key and a value have a meaning.
# # Configuration file for mbed. # MyKey1=This is a value for key1. MyKey2=Value 2 Message1 = This is a test message no.1 Message2 = This is a test message no.2 Message3 = This is a test message no.3
Reading
This example codes read a file named input.cfg on mbed local file system.
#include "mbed.h"
#include "ConfigFile.h"
LocalFileSystem local("local");
ConfigFile cfg;
int main(void) {
char *key = "MyKey";
char value[BUFSIZ];
/*
* Read a configuration file from a mbed.
*/
if (!cfg.read("/local/input.cfg")) {
error("Failure to read a configuration file.\n");
}
/*
* Get a configuration value.
*/
if (cfg.getValue(key, &value[0], sizeof(value))) {
printf("'%s'='%s'\n", key, value);
}
}
- Ignore comments in a configuration file.
- Ignore empty lines in a configuration file.
- Keep spaces in side of keys and values.
Writing
This example codes write a configuration to a file.
#include "mbed.h"
#include "ConfigFile.h"
LocalFileSystem local("local");
ConfigFile cfg;
int main(void) {
/*
* Set a configuration value.
*/
if (!cfg.setValue("MyKey", "TestValue")) {
error("Failure to set a value.\n");
}
/*
* Write to a file.
*/
if (!cfg.read("/local/output.cfg")) {
error("Failure to write a configuration file.\n");
}
}
Summary
You can use this library class if you want to read configuration variables or store a configuration variables.
2 comments
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Good Utility,
Thanks,
Warm Regards,
Boseji
http://m8051.blogspot.com