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Guide to PROGMEM on ESP8266 and Arduino IDE

Intro

On low memory devices like the arduino and esp8266 you do not want strings to be stored in RAM. This occurs by default on these systems. Declare a string const char * xyz = "this is a string" and it will use up RAM.

The solution on these devices is to allow strings to be stored in read only memory, in Arduino this is the PROGMEM macro. Most of my experience is with the ESP8266 which is a 32bit micros controller. This device stores PROGMEM data in flash. The macro PROGMEM on ESP8266 is simply

#define PROGMEM   ICACHE_RODATA_ATTR
@forairan
forairan / PhpJava.java
Last active Mar 14, 2020
This snippet of code is syntactically valid in both PHP and Java, and produces the same output in both.
View PhpJava.java
/*<?php
//*/public class PhpJava { public static void main(String[] args) { System.out.printf("/*%s",
//\u000A\u002F\u002A
class PhpJava {
static function main() {
echo(//\u000A\u002A\u002F
"Hello World!");
}}
//\u000A\u002F\u002A
PhpJava::main();
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