用逗号和字母分隔的字符串中的拆分值

Question

I am currently working with Arduino where I have a string, that for example looks like this:

"30,30,20,10,50,50M20"

I say for example, because the values can always change. The letter however will always be a 1 word letter. There will always be 7 numbers and 1 letter. The letter will always be in between value 6 and 8.

In that string there are different values and they are separated by both commas and also a letter which makes the solution it a bit more tricky.

If I break the string above I need to store it like this:

A = 30
B = 30
C = 20
D = 10
E = 50
F = 50
G = M
H = 20

These values regularly change (and the length of each value) so the code has to be setup in a way so it separates the values by the ',' and also the letter, in this case 'M' .

This is what I tried to do myself:

char c = Serial.read(); 
FindA = c.indexOf(',');
A = c.substring(0, ind1); 
FindB = c.indexOf(',', ind1+1 );       
B = c.substring(ind1+1, ind2+1);

And then somehow implement so it takes out the value before and after the letter (that also needs to be stored).

I have this outcommented too String recievedMessage += (char)Serial.read(); .

I am developing on an Arduino.

Answer 1

You can write a small parser for your string, like:

#include<cstdlib>
#include<cctype>
#include<iterator>
#include<vector>

std::vector<int> values(1);
char separator = ',';

// read every char from the stream and store it in i
for (int i = Serial.read(); i >= 0; i = Serial.read())
{
    // check if i is a digit (and if so, append it to the previous digit)
    if (std::isdigit(i))
    {
        values.back() = values.back() * 10 + std::atoi(i);
    }
    // check if i is a letter [A-Z][a-z]
    else if (std::isalpha(i))
    {
        values.back() = i;
        i = separator;
    }

    // check if i is the separator 
    if (i == separator)
    {
        values.push_back(0);
    }    
}

A = values[0];
B = values[1]
// ...

Answer 2

Assuming the strings are sent as lines (with a new line character \\n at the end).

typedef struct {
    int A = 0;
    int B = 0;
    int C = 0;
    int D = 0;
    int E = 0;
    int F = 0;
    char G = 0;
    int H = 0;
} Line;

typedef void (*LineHandler)(Line data);

bool line_parser(char c, LineHandler line_handler) {
    static Line data;
    static int value = 0;
    static byte state = 0;
    bool complete = false;

    // ignore the carriage return character
    if (c == '\r') return complete;

    if (state < 8) {
        if (isdigit(c)) {
            value = value*10 + c-'0';  // add the digit
        }
        else if (c == ',' || c == '\n') {
            // if a comma or end of line is found, save the value
            switch (state) {
                case 0: data.A = value; break;
                case 1: data.B = value; break;
                case 2: data.C = value; break;
                case 3: data.D = value; break;
                case 4: data.E = value; break;
                // the F and G are set when the letter is found
                case 7: data.H = value; break;
            }
            // advance the parsing state and reset the value
            state++;
            value = 0;
        }
        else if (state == 5 && isalpha(c)) { // if parsing the 6th number and a letter is found
            data.F = value; // save the 6th number
            data.G = c; // save the letter
            state += 2; // advance to parsing the 8th value
            value = 0; // reset the value
        }
        else
            state = 10; // unexpected character; stop the parser
    }
    if (c == '\n') {
        if (state == 8) {
            //got complete line
            line_handler(data);
            complete = true;
        }
        else {
            // parsing failed
        }
        // reset the parser
        value = 0;
        state = 0;
    }
    return complete;
}

void handle_line(Line data) {
    // just print out the data
    Serial.println("Line:");
    Serial.print("A = ");
    Serial.println(data.A);
    Serial.print("B = ");
    Serial.println(data.B);
    Serial.print("C = ");
    Serial.println(data.C);
    Serial.print("D = ");
    Serial.println(data.D);
    Serial.print("E = ");
    Serial.println(data.E);
    Serial.print("F = ");
    Serial.println(data.F);
    Serial.print("G = ");
    Serial.println(data.G);
    Serial.print("H = ");
    Serial.println(data.H);
    Serial.println();
}

void setup() {
    Serial.begin(115200);
}

void loop() {
    if (Serial.available()) {
        line_parser(Serial.read(), handle_line);
    }
}

This parser is non-blocking and is feed character by character and after it receives the whole line, it calls a function that should handle the parsed data.

Sending it:

54,125,11045,11,78,4H45
invalid line
11,22,33,44,55,66K88
30,30,20,10,50,50M20

should send back:

Line:
A = 54
B = 125
C = 11045
D = 11
E = 78
F = 4
G = H
H = 45

Line:
A = 11
B = 22
C = 33
D = 44
E = 55
F = 66
G = K
H = 88

Line:
A = 30
B = 30
C = 20
D = 10
E = 50
F = 50
G = M
H = 20