Splitting string with colons and spaces?

Question

So I've made my code work for separating the string:

    String c;
 
    for (int j = 0 ; j < count; j++) {
        c += ip(ex[j]);
    }
  
    return c;                      
}

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

I have had no luck with this, so any help would be greatly appreciated!

score 0 · Answer 1 · answered Dec 14 '21 at 04:35

I'd suggest using <regex> library if the compiler of yours supports C++11.

#include <fstream>
#include <iostream>
#include <algorithm>
#include <iterator>
#include <regex>

const std::regex ws_re(":| +");
void printTokens(const std::string& input)
{
    std::copy( std::sregex_token_iterator(input.begin(), input.end(), ws_re, -1),
               std::sregex_token_iterator(),
               std::ostream_iterator<std::string>(std::cout, "\n"));
}

int main()
{
    const std::string text1 = "...:---:...";
    std::cout<<"no whitespace:\n";
    printTokens(text1);

    std::cout<<"single whitespace:\n";
    const std::string text2 = "..:---:... ..:---:...";
    printTokens(text2);

    std::cout<<"multiple whitespaces:\n";
    const std::string text3 = "..:---:...   ..:---:...";
    printTokens(text3);
}

The description of library is on cppreference. If you are not familiar with regular expressions, the part in the code above const std::regex ws_re(":| +"); means that there should be either ':' symbol or (or in regular expressions denoted by pipe symbol '|') any amount of whitespaces ('+' stands for 'one or more symbol that stands before the plus sign'). Then one is able to use this regular expression to tokenize any input with std::sregex_token_iterator. For more complex cases than whitespaces, there is wonderful regex101.com.
The only disadvantage I could think of is that regex engine is likely to be slower than simple handwritten tokenizer.

Thank you for your input but this doesn't work on arduino IDE. — TTG TTG, Dec 14 '21 at 05:17

mmixLinus · Accepted Answer · 2021-12-14T12:25:11.763

I would simply add a delimiter to your tokenizer. From a strtok() description the second parameter "is the C string containing the delimiters. These may vary from one call to another".

So add a 'space' delimiter to your tokenization: ex[i] = strtok(NULL, ": "); trim any whitespace from your tokens, and throw away any empty tokens. The last two shouldn't be necessary, because the delimiters won't be part of your collected tokens.

Splitting string with colons and spaces?

2 Answers2