Split String into String array

Question

I have been playing around with programming for arduino but today i\'ve come across a problem that i can\'t solve with my very limited C knowledge. Here\'s how it goes. I\'m

Answer 1

Implementation:

int sa[4], r=0, t=0;
String oneLine = "123;456;789;999;";

for (int i=0; i < oneLine.length(); i++)
{ 
 if(oneLine.charAt(i) == ';') 
  { 
    sa[t] = oneLine.substring(r, i).toInt(); 
    r=(i+1); 
    t++; 
  }
}

Result:

    // sa[0] = 123  
    // sa[1] = 456  
    // sa[2] = 789  
    // sa[3] = 999

Answer 2

The C way to split a string based on a delimiter is to use strtok (or strtok_r). See also this question.

Answer 3

For dynamic allocation of memory, you will need to use malloc, ie:

String returnvalue[splitcount];
for(int i=0; i< splitcount; i++)
{
    String returnvalue[i] = malloc(maxsizeofstring * sizeof(char));
}

You will also need the maximum string length.

Answer 4

This is an old question, but i have created some piece of code that may help:

 String getValue(String data, char separator, int index)
{
  int found = 0;
  int strIndex[] = {0, -1};
  int maxIndex = data.length()-1;

  for(int i=0; i<=maxIndex && found<=index; i++){
    if(data.charAt(i)==separator || i==maxIndex){
        found++;
        strIndex[0] = strIndex[1]+1;
        strIndex[1] = (i == maxIndex) ? i+1 : i;
    }
  }

  return found>index ? data.substring(strIndex[0], strIndex[1]) : "";
}

This function returns a single string separated by a predefined character at a given index. For example:

String split = "hi this is a split test";
String word3 = getValue(split, ' ', 2);
Serial.println(word3);

Should print 'is'. You also can try with index 0 returning 'hi' or safely trying index 5 returning 'test'.

Hope this help!

Answer 5

I think your idea is a good start point. Here is a code that i use (to parse HTTP GET REST requests with an Ethernet shield).

The idea is to use a while loop and lastIndexOf of and store the strings into an array (but your could do something else).

"request" is the string you want to parse (for me it was called request because.. it was).

    int goOn = 1;
    int count = -1;
    int pos1;
    int pos2 = request.length();

    while( goOn == 1 ) {
        pos1 = request.lastIndexOf("/", pos2);
        pos2 = request.lastIndexOf("/", pos1 - 1);

        if( pos2 <= 0 ) goOn = 0;

        String tmp = request.substring(pos2 + 1, pos1);

        count++;
        params[count] = tmp;

        // Serial.println( params[count] );

        if( goOn != 1) break;
    }
    // At the end you can know how many items the array will have: count + 1 !

I have used this code successfully, but i thing their is an encoding problem when i try to print params[x]... i'm alos a beginner so i don't master chars vs string...

Hope it helps.

Answer 6

I believe this is the most straight forward and quickest way:

String strings[10]; // Max amount of strings anticipated

void setup() {
  Serial.begin(9600);
  
  int count = split("L,-1,0,1023,0", ',');
  for (int j = 0; j < count; ++j)
  {
    if (strings[j].length() > 0)
      Serial.println(strings[j]);
  }
}

void loop() {
  delay(1000);
}

// string: string to parse
// c: delimiter
// returns number of items parsed
int split(String string, char c)
{
  String data = "";
  int bufferIndex = 0;

  for (int i = 0; i < string.length(); ++i)
  {
    char c = string[i];
    
    if (c != ',')
    {
      data += c;
    }
    else
    {
      data += '\0';
      strings[bufferIndex++] = data;
      data = "";
    }
  }

  return bufferIndex;
}