Question

我是C ++的初学者，但对于我的arduino，我需要这段代码。它正在编译和工作较低版本的arduino，例如Arduino的1.6.5.r5。从1.6.9开始，甚至最新版本的arduino（1.6.11），此声明不再编译。我完全不明白这个错误。可以用另一种方式重写吗？我正在使用一个库CallBack.h。

图书馆的来源： https://bitbucket.org/ehsmaes/cmdcallback/wiki/Home

来自库的示例 `

#include <CallBack.h>
// Compile and upload to arduino. Run the serial monitor and type command
// :help;
// Values for initiation of cmd/response interface. 
// After initial boot, id, gid and del are stored in eeprom.
// Change values by command. Make sure each device has a unique id.
String descr="Command/response test program v0.1";
String id="a1";
String gid="a";
int    del=0; //delayed response

// List of commands defined by keyword, funtion pointer, number of arguments 
// and description used in "help" command.
CallBackDef f[] = {
  {(String)"add",   (FunctionPointer)&add,  (int)2, (String)":num1:num2"}
};

// initiate command handler: function array, number of functions and intial values
CallBack cmd(f, sizeof(f) / sizeof(*f), id, gid, descr, del);

void setup() {
  Serial.begin(9600);
  cmd.ok(); // say hello
}

void loop() {
  // Put code here. Use timers instead of delay if possible as not to disrupt
  // command/response interaction with host
}

void serialEvent() {
  // Don't forget this line. Parse command if serial data is available.
  cmd.cmdCheck();
}

//   --------- command initiated callback functions below ---------
// callback functions all need to be defined void and with String argv
// argument list. The command parser will validate the number of input
// parameters but any additional validation has to be perfomed by each
// callback function. As the argument list is passed as strings, type
// casting to other types is the responsibility of the function.


void add(String argv[]) {
  int a = cmd.stoi(argv[0]);
  int b = cmd.stoi(argv[1]);
  cmd.respond(String(a + b));
}

`

    CmdCallBack_example_minimum:17: error: 'add' was not declared in this scope
   {(String)"add",   (FunctionPointer)&add,  (int)2, (String)":num1:num2"}
                                       ^
Using library CmdCallBack in folder: /Users/adrian/ownCloud/Arduino/libraries/CmdCallBack (legacy)
exit status 1
'add' was not declared in this scope

Answer 1

此错误表示未在baseevent之前声明函数CallBackDef f[] = ...。在使用之前需要函数原型，或函数定义（在使用之前完成函数）。

Arduino中还有另一个预处理器，它负责这些定义并将它们放在草图开始周围。但是任何更复杂的东西通常都会被破坏（生成的原型完全错误），所以即使合法的c ++代码也无法编译。它有时会改变它在Arduino版本之间的行为。

示例CmdCallBack_example_minimum在1.6.9中默认不起作用，但是，如果添加函数原型：

#include <CallBack.h>

// Compile and upload to arduino. Run the serial monitor and type command
// :help;

// Values for initiation of cmd/response interface. 
// After initial boot, id, gid and del are stored in eeprom.
// Change values by command. Make sure each device has a unique id.
String descr="Command/response test program v0.1";
String id="a1";
String gid="a";
int    del=0; //delayed response
byte   echo=1; // command back to host

// ------------------------------------------------
// Function Prototype for add:
void add(String argv[]);

// List of commands defined by keyword, funtion pointer, number of arguments 
// and description used in "help" command.
CallBackDef f[] = {
  {(String)"add",   (FunctionPointer)&add,  (int)2, (String)":num1:num2"}
};

// initiate command handler: function array, number of functions and intial values
CallBack cmd(f, sizeof(f) / sizeof(*f), id, gid, descr, del, echo);

void setup() {
  Serial.begin(9600);
  cmd.ok(); // say hello
}

void loop() {
  // Don't forget this line. Parse command if serial data is available.
  cmd.cmdCheck();

  // Put code here. Use timers instead of delay if possible as not to disrupt
  // command/response interaction with host


}

//   --------- command initiated callback functions below ---------
// callback functions all need to be defined void and with String argv
// argument list. The command parser will validate the number of input
// parameters but any additional validation has to be perfomed by each
// callback function. As the argument list is passed as strings, type
// casting to other types is the responsibility of the function.

void add(String argv[]) {
  int a = cmd.stoi(argv[0]);
  int b = cmd.stoi(argv[1]);
  cmd.respond(String(a + b));
}

如果没有显式函数原型，Arduino预处理器会处理它，但它会在使用它的行之后插入。所以仍然有错误。

然而，即使在修复后（CallBack cmd中的某些不正确的参数类型......）

，您的版本也会被破坏

声明函数指针C ++ arduino 1.6.11

1 个答案: