Arduino操作员 [英] Operator new for Arduino

问题描述

我已收到通知（特别是在回答Arduino上的 C ++标准库 和Stack Overflow问题 C ++ string和Arduino String。如何组合它们？ ）），Arduino编译器不实现 new 运算符。但是，我为Arduino编写了一个程序（在Arduino IDE中），它使用它，它工作得很好。

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");
}

下面是一个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.

那么为什么我会不断听到这个？这些人是错误的，还是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 定义为Arduino分发的一部分：
/ 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。这些运算符在AVR Libc中没有定义。我对这些设计选择的解释：Libc人认为这是一个坏主意，而Arduino人都是关于易用性：如果你想要 new 和删除，请给他们。

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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