获取指定字符数组arduino的前n个元素 [英] getting the first n elements of a specified char array arduino

问题描述

我的目标是从串行读取一些字符串，例如 234124!3455addg#5867 如果程序看到 !它应该开始将它添加到一个字符数组，如果它看到 # 它应该返回该字符数组的前 4 个元素，对于我的示例，返回值应该是 3455.我该如何解决?我使用 String 类做了这个，但我需要将它实现为 char 数组.我对arduino很陌生，所以请清楚谢谢.这是我的代码:

My aim is reading some string from serial for example 234124!3455addg#5867 if the program sees ! it should start to add it to a char array and if it sees # it should return the first 4 elements of that char array for my example the return should be 3455. How can I solve it? I made this using String class but I need to implement it to char array. I am quite new on arduino so please be clear thank you. Here is my code:

const char *s = "123123123!0037selam#aaaaSDSDa";
const char *CHAR1 = "!";
const char *CHAR2 = "#";

char *target = NULL;
char *start, *end;

void setup() {
    Serial.begin(9600);
}

void loop() {
    if ( start = strstr( s, CHAR1 ) )
    {
        start += strlen( CHAR1 );
        if ( end = strstr( start, CHAR2 ) )
        {
            target = ( char * )malloc( end - start + 1 );
            memcpy( target, start, end - start );
            target[end - start] = '\0';
        }
    }

    if ( target )
    {
        for(int i=0; i<4;i++)
            Serial.print( target[i]);
    }

    free( target );
    return 0;
}

推荐答案

我认为这是一种更简单的方法.这取决于是否有未明确说明的要求.

Here's a simpler way of going about it, I think. It depends on whether or not there are requirements that aren't explicitly stated.

一些值得一提的事情，

1. 您想返回跟在 '!' 之后的前 4 个字节，所以您只需要缓冲 4 个字符
2. 我暂时没有准备好所有的电缆，所以我只是撞在一起的东西可以在 PC 上运行.在你的情况下，而不是返回您刚刚输出的字符串缓冲区的副本Serial.print

代码:

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

class dummy
{
    public:
        dummy()
        {
            const char *testData = "234124!3455addg#5867";
            int dataLen = strlen(testData);
            mData = new char[dataLen+1];
            strcpy(mData, testData);
            mTotal = strlen(testData);
            mIndex = 0;
        }
        int available()
        {
            return mTotal - mIndex;
        }
        char read()
        {
            return mData[mIndex++];
        }
    private:
        char *mData;
        int mIndex;
        int mTotal;
};

char *testFunc()
{
    dummy *Serial = new dummy();
/// -------- 8< ------------ cut here until the next pair of scissors. put inside the loop function
/// your code does all of the functionality (reading and buffering) inside a single iteration of loop(). 
/// Normally, I'd expect a single character to be read each time. I'd expect loop() to be 
/// run 16 times before a result was output, since # is the 16th character of the string.
    char tmpBuffer[5] = {0};
    int bufferIndex = 0;
    bool marker1Seen = false;

    while (Serial->available() > 0)
    {
        char received = Serial->read();
        if (received == '!')
        {
            marker1Seen = true;
        }

        else if (received == '#')
        {
            return strdup(tmpBuffer);
        }

        else if (marker1Seen == true && bufferIndex < 4)
        {
            tmpBuffer[bufferIndex++] = received;
        }
    }
    // shouldn't get here if the input is well-formed
    return NULL;
/// -------- 8< ------------ cut here
}

int main()
{
    char *result = testFunc();
    cout << result;
    delete result;
}

这篇关于获取指定字符数组arduino的前n个元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！