🚀 解析Arduino蜂鸣器旋律播放代码！🎵 适合初学者

在《Arduino入基础到实践》书中第十二个项目中我有一点不明白就是为什么取得长度要为数组个数的一半

length = sizeof（tune）/ sizeof（tune [0]）;

然后书中给出的解释是：
Arduino从入门基础到实践书中第十二个项目蜂鸣器旋律发声图1

在播放的时，数组有26个元素只调取了一半13个元素，不太明为什么要这样处理

      for (int x = 0; x < length; x++)
      {
            tone (8, tune[x]);
            delay(1500 * duration[x]);
            noTone(8);
      }
      delay(5000);

[mw_shl_code=c,true]#include "Arduino.h"

//项目12蜂鸣器发声旋律演奏
#define NOTE_C3             131
#define NOTE_CS3       139
#define NOTE_D3             147
#define NOTE_DS3       156
#define NOTE_E3             165
#define NOTE_F3             175
#define NOTE_FS3       185
#define NOTE_G3             196
#define NOTE_GS3       208
#define NOTE_A3             220
#define NOTE_AS3       233
#define NOTE_B3             247
#define NOTE_C4             262
#define NOTE_CS4       277
#define NOTE_D4             294
#define NOTE_DS4       311
#define NOTE_E4             330
#define NOTE_F4             349
#define NOTE_FS4       370
#define NOTE_G4             392
#define NOTE_GS4       415
#define NOTE_A4             440
#define NOTE_AS4       466
#define NOTE_B4             494

#define WHOLE             1
#define HALF             0.5
#define QUARTER             0.25
#define EIGHTH             0.125
#define SIXTEENTH       0.0625

int tune[] = { NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_B3, NOTE_G3,
                                 NOTE_A3, NOTE_C4, NOTE_C4, NOTE_G3, NOTE_G3, NOTE_G3, NOTE_F3, NOTE_F3, NOTE_G3, NOTE_F3,
                                 NOTE_E3, NOTE_G3, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_C4, NOTE_A3, NOTE_B3, NOTE_B3, NOTE_C4, NOTE_D4

                                 };
float duration[] = { EIGHTH, QUARTER+EIGHTH, SIXTEENTH, QUARTER, QUARTER, HALF,
                                       HALF, HALF, QUARTER, QUARTER, HALF+QUARTER, QUARTER, QUARTER, QUARTER,
                                       QUARTER, QUARTER, QUARTER, HALF+QUARTER
                                    };

int length;

//The setup function is called once at startup of the sketch
void setup()
{
// Add your initialization code here
      pinMode(8, OUTPUT);
      length = sizeof(tune) / sizeof(tune[0]);
//       length = sizeof(tune);
}

// The loop function is called in an endless loop
void loop()
{
//Add your repeated code here
      for (int x = 0; x < length; x++)
      {
            tone (8, tune[x]);
            delay(1500 * duration[x]);
            noTone(8);
      }
      delay(5000);
}
[/mw_shl_code]

Arduino从入门基础到实践书中 第十二个项目 蜂鸣器旋律发声

Arduino从入门基础到实践书中第十二个项目蜂鸣器旋律发声