我正在使用Arduino的PTP（ISO 15740）库（通过USB主机操纵相机设置）。它使用此常量，似乎是某种哈希表数组。问题是我不知道它叫什么，所以我不确定如何在线搜索它，并且由于我不是一个经验丰富的C ++程序员，所以我不知道如何使用它。这是如何运作的？
const ValueTitle<VT_SHSPEED, VT_SHSPEED_TEXT_LEN> ShutterSpeedTitles[] PROGMEM =
{
{0x0c, {'B','u','l','b',0} },
{0x10, {' ','3','0','"',0} },
{0x13, {' ','2','5','"',0} },
{0x14, {' ','2','0','"',0} },
{0x15, {' ','2','0','"',0} },
{0x18, {' ','1','5','"',0} },
{0x1B, {' ','1','3','"',0} },
{0x1C, {' ','1','0','"',0} },
{0x1D, {' ','1','0','"',0} },
{0x20, {' ',' ','8','"',0} },
{0x23, {' ',' ','6','"',0} },
{0x24, {' ',' ','6','"',0} },
{0x25, {' ',' ','5','"',0} },
{0x28, {' ',' ','4','"',0} },
{0x2B, {' ','3','"','2',0} },
{0x2C, {' ',' ','3','"',0} },
{0x2D, {' ','2','"','5',0} },
{0x30, {' ',' ','2','"',0} },
{0x33, {' ','1','"','6',0} },
{0x34, {' ','1','"','5',0} },
{0x35, {' ','1','"','3',0} },
{0x38, {' ',' ','1','"',0} },
{0x3B, {' ','0','"','8',0} },
{0x3C, {' ','0','"','7',0} },
{0x3D, {' ','0','"','6',0} },
{0x40, {' ','0','"','5',0} },
{0x43, {' ','0','"','4',0} },
{0x44, {' ','0','"','3',0} },
{0x45, {' ','0','"','3',0} },
{0x48, {' ',' ',' ','4',0} },
{0x4B, {' ',' ',' ','5',0} },
{0x4C, {' ',' ',' ','6',0} },
{0x4D, {' ',' ',' ','6',0} },
{0x50, {' ',' ',' ','8',0} },
{0x53, {' ',' ','1','0',0} },
{0x54, {' ',' ','1','0',0} },
{0x55, {' ',' ','1','3',0} },
{0x58, {' ',' ','1','5',0} },
{0x5B, {' ',' ','2','0',0} },
{0x5C, {' ',' ','2','0',0} },
{0x5D, {' ',' ','2','5',0} },
{0x60, {' ',' ','3','0',0} },
{0x63, {' ',' ','4','0',0} },
{0x64, {' ',' ','4','5',0} },
{0x65, {' ',' ','5','0',0} },
{0x68, {' ',' ','6','0',0} },
{0x6B, {' ',' ','8','0',0} },
{0x6C, {' ',' ','9','0',0} },
{0x6D, {' ','1','0','0',0} },
{0x70, {' ','1','2','5',0} },
{0x73, {' ','1','6','0',0} },
{0x74, {' ','1','8','0',0} },
{0x75, {' ','2','0','0',0} },
{0x78, {' ','2','5','0',0} },
{0x7B, {' ','3','2','0',0} },
{0x7C, {' ','3','5','0',0} },
{0x7D, {' ','4','0','0',0} },
{0x80, {' ','5','0','0',0} },
{0x83, {' ','6','4','0',0} },
{0x84, {' ','7','5','0',0} },
{0x85, {' ','8','0','0',0} },
{0x88, {'1','0','0','0',0} },
{0x8B, {'1','2','5','0',0} },
{0x8C, {'1','5','0','0',0} },
{0x8D, {'1','6','0','0',0} },
{0x90, {'2','0','0','0',0} },
{0x93, {'2','5','0','0',0} },
{0x94, {'3','0','0','0',0} },
{0x95, {'3','2','0','0',0} },
{0x98, {'4','0','0','0',0} },
{0x9B, {'5','0','0','0',0} },
{0x9C, {'6','0','0','0',0} },
{0x9D, {'6','4','0','0',0} },
{0xA0, {'8','0','0','0',0} }
};
本质上，我最终要寻找的是这个。十六进制值表示相机上的快门速度。如果在摄像机显示屏上以单字符形式显示，则十六进制亨伯右侧的数据就是快门速度的值。 （我猜这可以称为矩阵？）。我想插入设备，然后在相机上设置曝光度。我们说一秒钟的曝光，它用十六进制值“ 0x38”表示。这是一个起点参考。
我想拍五张照片。其中之一是“ 0x38”，而其他四个是在此之前的两次曝光，另外两个是在此之后的两次曝光。因此，我想按顺序将所有五个十六进制值放入一个数组中，以便找到“ 0x38”，然后在下面搜索两个，然后在下面找到一个，然后是引用，然后在上面一个，然后在上面两个。
最佳答案
这是一个数组初始化器：
例：
int val[] = {1, 2, 3, 4}; // initializes an array of ints.
如果您具有struct，则语法相同。
struct X
{
int x;
int y;
};
X valX[] = { {1,2}, {3,4}, {5,6}}; // initializes an array of X
// first X is {1,2}
// second X is {3,4}
// etc
在您的情况下，结构为：
ValueTitle<VT_SHSPEED, VT_SHSPEED_TEXT_LEN>
但是概念是相同的。
关于c++ - 我不明白这种C++语法，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13212199/