Efficient Hash Map Implementation for String-to-Object Mapping
Info
The Efficient Hash Map Implementation for String-to-Object Mapping is a Library for MetaTrader 4 that this is a hash map implementation that allows string indexes, similar to arrays. It maps strings to objects, where the objects must be a subclass of the provided HashValue class.
Usage
This tool is typically used for enhancing chart analysis and decision making.
Platform
This Library works exclusively on MetaTrader 4 (both build 600+ and newer versions).
Setup
Place the downloaded file in MQL4/Libraries folder via File ? Open Data Folder in MetaTrader 4.
How to Install and Use Efficient Hash Map Implementation for String-to-Object Mapping
1. Storage: Place library files in the MQL/Libraries directory to ensure they are accessible to your projects.
2. Implementation: Include the library in your code using the #import directive, ensuring you match the exact function names and parameters.
3. Compilation: Ensure the library is present in the directory before you compile your main EA or script, as the compiler links them during this phase.
4. Management: Keep libraries organized in sub-folders if you manage many custom functions to maintain a clean project structure.
Frequently Asked Questions
Q: What is a library file used for? A: Libraries store reusable code modules, allowing you to centralize common logic used by multiple EAs or indicators.
Q: Is a library executable? A: No, libraries are non-executable files containing functions; they must be imported into an EA, indicator, or script to function.
Q: Can I update a library while the platform is running? A: You should compile your EA or script after updating a library to ensure the latest code changes are integrated.
What this tool does
This is a hash map implementation that allows string indexes, similar to arrays.
Typical Use Case
This Library excels in automated trading and technical analysis on MetaTrader 4.
Compatible Platform & Setup
This Library works on MetaTrader 4. Place the file in the MQL4/Libraries folder and restart the terminal.
Description & Settings
Related: log4mql(mini) mt4 - another powerful library for MetaTrader 4 traders.
This is a hash map implementation that allows string indexes, similar to arrays. It maps strings to objects, where the objects must be a subclass of the provided HashValue class.Also recommended: the high low week library - similar library with strong performance on MetaTrader 4.
By default, the hash map adopts the value objects. This means it will free the memory for these objects when they are no longer in the hash. This behavior can be disabled in the constructor.
The codebase version may not be the most recent. The latest version can be found via the provided link.
Documentation:
Hash Class
HashLoop Class
Version
125
Below is an example, which is also utilized in our JSON parser class to represent JSON objects.
hash *h = new hash();
// Store values
h.hputint("low", 0);
h.hputint("high", 1);
// Get values
int high = h.ggetint("high");
// Loop
hashloop *l;
for ( l = new hashloop(h) ; l.hasnext() ; l.next()) {
string key = l.key();
int j = l.valint();
print(key, " = ", j);
}
delete l;
delete h;
You may also like: time suite - excellent alternative for library users on MetaTrader 4.
Source Code
#ifndef ydrol_hash_mqh
#define ydrol_hash_mqh
/*
this is losely ported from a c version i have which was in turn modified from hashtable.c by christopher clark.
copyright (c) 2014, andrew lord (nickname=lordy) <[email protected]>
copyright (c) 2002, 2004 christopher clark <[email protected]>
2014/02/21 - readded primenumber sizes and auto rehashing when load factor hit.
*/
class hashvalue {
};.......
⚠ Limitations & Risk Warning
- This tool is provided for educational and testing purposes only.
- Past performance does not guarantee future results.
- Trading involves substantial risk of loss. Use on a demo account first.
- Results may vary depending on market conditions, broker, and settings.
- We recommend thorough backtesting and forward testing before using with real funds.