Arduino初学者问题

Question

我对Arduino是个新手，而且还在用例子做实验。在使用以下代码时，我遇到了一些问题：

#include <ctype.h>
#include <Arduino.h>
#include "Telegraph.h"
//#include <Telegraph.h>

char* LETTERS[]  =  {
  ".-", "-...", "-.-.", "-..", ".",      // A-E
  "..-.", "--.", "....", "..", ".---",   // F-J
  "-.-", ".-..", "--", "-.", "---",      // K-O
  ".--.", "--.-", ".-.", "...", "-",     // P-T
  "..-", "...-", ".--", "-..-", "-.--",  // U-Y
  "--.."                                 // Z
};

char* DIGITS[]  =  {
  "-----", ".----", "..---", "...--",     //0-3
  "....-", ".....", "-....", "--...",     //4-7
  "---..", "----."                        //8-9
};

Telegraph::Telegraph(const int outputPin, const int ditLength){
  _outputPin  =  outputPin;
  _ditLength  =  ditLength;
  _dahLength  =  dahLength;
  pinMode(_outputPin, OUTPUT);
}

void Telegraph::outputCode(const char* code){
  for(int i=0; i<strlen(code); i++){
    if( code[i]  ==  '.' )
      dit();
    else
      dah();
  }
}

void Telegraph::dit(){
  Serial.print(".");
  outputSymbol(_ditLength);
}

void Telegraph::dah(){
  Serial.print("-");
  outputSymbol(_dahLength);
}

void Telegraph::outputSymbol(const int length){
  digitalWrite(_outputPin, HIGH);
  delay(length);
  digitalWrite(_outputPin, LOW);
  delay(length);
}

void Telegraph::sendMessage(const char* message){
  for(int i=0;  i  <  strlen(message); i++){
    const char currentChar  =  toupper(message[i]);
    if( isalpha(currentChar) ){
      outputCode(LETTERS[currentChar  -  'A']);
      delay(_dahLength);
    }else if(isdigit(currentChar) ){
      outputCode(DIGITS[currentChar  -  '0']);
      delay(_dahLength);
    }else if(currentChar  =  ' '){
      Serial.print(" ");
      delay(_ditLength * 7);
    }
  }
  Serial.println();
}

我得到以下错误：

Telegraph.cpp:6:15: error: two or more data types in declaration of ‘LETTERS’
Telegraph.cpp: In constructor ‘Telegraph::Telegraph(int, int)’:
Telegraph.cpp:24:18: error: ‘dahLength’ was not declared in this scope
Telegraph.cpp: In member function ‘void Telegraph::sendMessage(const char*)’:
Telegraph.cpp:58:18: error: ‘LETTERS’ was not declared in this scope
Telegraph.cpp:63:30: error: assignment of read-only variable ‘currentChar’

如果这个问题太笼统，我很抱歉，但正如我前面提到的，我是个新手，不完全理解代码。

Answer 1

Telegraph.cpp:6:15:错误：“LETTERS”的声明中有两个或多个数据类型

在其他地方，符号LETTERS已经被定义了。也许是在Telegraph.h？你必须去寻找它。

Telegraph.cpp: In constructor ‘Telegraph::Telegraph(int, int)’:
Telegraph.cpp:24:18: error: ‘dahLength’ was not declared in this scope

相关代码：

  _dahLength  =  dahLength;

是的，dahLength没有定义。也许您想将其作为另一个参数添加到构造函数中？

Telegraph.cpp: In member function ‘void Telegraph::sendMessage(const char*)’:
Telegraph.cpp:58:18: error: ‘LETTERS’ was not declared in this scope

关于这个问题，请看上面的。解决第一个问题，忽略这个问题很久了。

Telegraph.cpp:63:30: error: assignment of read-only variable ‘currentChar’

这是由于

}else if(currentChar  =  ' '){

我确信您想使用==而不是=。