Arduino 的新操作员 [英] Operator new for Arduino

问题描述

有人告诉我(特别是在 一个对 Arduino 上的 C++ 标准库 和堆栈溢出问题的回答 C++ 字符串和 Arduino 字符串.如何组合它们?)) Arduino 编译器没有实现 new操作员.但是，我已经为使用它的 Arduino(在 Arduino IDE 中)编写了一个程序，并且运行良好.

I've been told (specifically in an answer to C++ Standard Library on Arduino, and in Stack Overflow question C++ string and Arduino String. How to combine them?)) that the Arduino compiler does not implement the new operator. However, I've written a program for the Arduino (in the Arduino IDE) which uses it, and it works perfectly.

void setup() {
    Serial.begin(9600);
}

void loop() {
    char* array;
    char c;
    unsigned arraySize;

    Serial.write("Enter a 1 digit number.\n");

    do {
        c = Serial.read();
    } while(c < '0' or c > '9');
    arraySize = c-'0';

    Serial.write("You wrote ");
    Serial.write(c);
    Serial.write(".\n");
    Serial.write("Now enter ");
    Serial.write(c);
    Serial.write(" lower-case letters.\n");

    array = new char[arraySize];

    for (unsigned i = 0; i < arraySize;) {
        array[i] = Serial.read();
        if (array[i] >= 'a' and array[i] <= 'z')
            i++;
    }

    Serial.write("You entered: ");

    for (unsigned i = 0; i < arraySize; i++) {
        Serial.write(array[i]);
        Serial.write(" ");
    }
    Serial.write("\n");
}

以下是演示其功能的示例输出:

Here is a sample output to demonstrate its functionality:

Enter a 1 digit number.
You wrote 5.
Now enter 5 lower-case letters.
You entered: h e l l o
Enter a 1 digit number.
You wrote 9.
Now enter 9 lower-case letters.
You entered: w a s s u p m a n
Enter a 1 digit number.
You wrote 9.
Now enter 9 lower-case letters.
You entered: h o w y a d o i n
Enter a 1 digit number.
You wrote 4.
Now enter 4 lower-case letters.
You entered: c o o l
Enter a 1 digit number.
You wrote 7.
Now enter 7 lower-case letters.
You entered: i t w o r k s
Enter a 1 digit number.

那为什么我总是听到这个?这些人是错的，还是我只是误解了他们的意思?

So why do I keep hearing this? Are these people wrong, or do I simply misunderstand their meaning?

推荐答案

new 和 delete 被定义为 Arduino 发行版的一部分:/usr/share/arduino/hardware/arduino/cores/arduino/new.h:

new and delete is defined as part of the Arduino distribution: /usr/share/arduino/hardware/arduino/cores/arduino/new.h:

/* Header to define new/delete operators as they aren't provided by avr-gcc by default
   Taken from http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=59453 
 */
#ifndef NEW_H
#define NEW_H

#include <stdlib.h>

void * operator new(size_t size);
void operator delete(void * ptr); 

__extension__ typedef int __guard __attribute__((mode (__DI__)));

extern "C" int __cxa_guard_acquire(__guard *);
extern "C" void __cxa_guard_release (__guard *);
extern "C" void __cxa_guard_abort (__guard *); 

extern "C" void __cxa_pure_virtual(void);

#endif

new.h 包含在 Printable.h 中，因此您可以在 Arduino 基本包含中获取它.不过，这些运算符并未在 AVR Libc 中定义.我对这些设计选择的解释:Libc 人认为这是一个坏主意，而 Arduino 人则是关于易用性:如果你想要 new 和 delete，请

The new.h is included in Printable.h so you are getting it in your Arduino basic includes. These operators are not defined in AVR Libc though. My interpretation of these design choices: the Libc people thought it was a bad idea, whereas Arduino people are all about ease of use: if you want new and delete, please have them.

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