Comma-Separated String to Array

How can I convert a comma-separated string to an array?

var array = string.split(',');

MDN reference, mostly helpful for the possibly unexpected behavior of the limit parameter. (Hint: "a,b,c".split(",", 2) comes out to ["a", "b"], not ["a", "b,c"].)

How to split a comma-separated string?

You could do this:

String str = "...";
List<String> elephantList = Arrays.asList(str.split(","));

Basically the .split() method will split the string according to (in this case) delimiter you are passing and will return an array of strings.

However, you seem to be after a List of Strings rather than an array, so the array must be turned into a list by using the Arrays.asList() utility. Just as an FYI you could also do something like so:

String str = "...";
ArrayList<String> elephantList = new ArrayList<>(Arrays.asList(str.split(","));

But it is usually better practice to program to an interface rather than to an actual concrete implementation, so I would recommend the 1st option.

Split a comma-delimited string into an array?

Try explode:

$myString = "9,admin@example.com,8";
$myArray = explode(',', $myString);
print_r($myArray);

Output :

Array
(
    [0] => 9
    [1] => admin@example.com
    [2] => 8
)

Converting a comma separated string into an array

Modify the string so that it's valid JSON, then JSON.parse() it:

var str = '"alpha", "beta", "gamma", "delta"';var json = '[' + str + ']';var array = JSON.parse(json);
console.log(array[0])

how to convert array of object to comma separated array of object

Why not! just turn it to JSON format, then remove open or closed square-brackets:

let arr = [{name:"k"},{name:"p"}];
console.log(JSON.stringify(arr).replace(/\[|\]/g,''))

Result as expected: {"name":"k"},{"name":"p"}

split and flatten array of comma separated strings

In this case you could just join and split again:

const a = ["jan,feb,may", "apr,may,sept,oct", "nov,jan,mar", "dec", "oct,feb,jan"];

const res = a.join().split(',');

console.log(res);

How to convert array into comma separated string in javascript

The method array.toString() actually calls array.join() which result in a string concatenated by commas. ref

var array = ['a','b','c','d','e','f'];document.write(array.toString()); // "a,b,c,d,e,f"

How to arrange comma separated string in Arrays of String in c?

You have several issues to work through to convert your function from simply printing the separated strings to stdout to saving the separated strings in ArrayOfString. Before getting to the changes, let's avoid using magic numbers in your code.

char ArrayOfString[10][5];

In ArrayOfString above, 10 and 5 are magic numbers. They are hardcoded values that will govern everything from the declaration size to required validation checks to protect your array bounds. Instead of hardcoding values, if you need a constant, define one (or more), e.g.

#include <stdio.h>
#include <string.h>

#define ROW 10
#define COL  5

char ArrayOfString[ROW][COL];

Now on to separating your string into tokens. The C-library provides a function specifically tailored to separating delimited strings into tokens. Conveniently named strtok. The only caveat to know about strtok is that it modifies the string, so if you need to preserve the original, make a copy first.

To use strtok (string, delims) to separate string into tokens at delims, your first call to strtok takes string as the 1st parameter. All subsequent calls use NULL in its place. You can either make an initial call to strtok and then use a while loop to complete the process, or a for loop is tailor made for handling the initial call, as well as all subsequent calls with NULL.

For example your function utilizing strtok to separate string into tokens and providing a size_t return of the number of tokens copied to ArrayOfString could be similar to:

char ArrayOfString[ROW][COL];

size_t vSeparateSringByComma (char* string)
{
    const char *delims = ",\n";
    char *s = string;
    size_t n = 0, len;

    for (s = strtok (s, delims); s && n < ROW; s = strtok (NULL, delims))
        if ((len = strlen (s)) < COL)
            strcpy (ArrayOfString[n++], s);
        else
            fprintf (stderr, "error: '%s' exceeds COL - 1 chars.\n", s);

    return n;
}

(note: how your array bounds are protected both by the check with n < ROW and each row array bound is protected with (len = strlen (s)) < COL before the copy to ArrayOfString[n++] is made)

(also note: how by not using magic numbers, if you change the ROW or COL size in the future, only the constants need changing and the change is automatically incorporated throughout your code by virtue of using constants)

Your example program would then be:

int main(void) {

    char string[] = "$,0,3,307,183,18,5,119,1,#";
    size_t n = vSeparateSringByComma (string);

    for (size_t i = 0; i < n; i++)
        printf ("ArrayOfString[%zu] : '%s'\n", i, ArrayOfString[i]);
}

Example Use/Output

$ ./bin/arrayofstrings
ArrayOfString[0] : '$'
ArrayOfString[1] : '0'
ArrayOfString[2] : '3'
ArrayOfString[3] : '307'
ArrayOfString[4] : '183'
ArrayOfString[5] : '18'
ArrayOfString[6] : '5'
ArrayOfString[7] : '119'
ArrayOfString[8] : '1'
ArrayOfString[9] : '#'

Using strcspn and strspn Instead of strtok

As discussed in the comments, using strcspn to report the number of sequential characters not containing a delimiter allowing you to determined the length of each field. You then need to skip over the delimiters (which in many cases can be made up of more than one delimiter (e.g. $, 0, 3, ...).

While strtok considers multiple sequential delimiters a single delimiter, you would need a similar way to skip over the intervening delimiters to position your self to read the next field. strspn will work nicely using the same delims, but this time reporting the number of characters made up of only characters within delims (allowing you to add that to your len and then len to s to position yourself for the next read)

A short variation using strcspn and strspn could be:

size_t vSeperateSringByComma (char* string)
{
    const char *delims = ",\n";
    char *s = string;
    size_t n = 0, len;

    while ((len = strcspn (s, delims))) {   /* number of non-delim chars */
        if (len < COL) {                    /* validate it will fit */
            memcpy (ArrayOfString[n], s, len);  /* copy len chars */
            ArrayOfString[n++][len] = 0;    /* nul terminate at len */
        }
        else
            fprintf (stderr, "error: '%s' exceeds COL - 1 chars.\n", s);

        len += strspn (s + len, delims);    /* scan past delimiter(s) */
        s += len;               /* update s to beginning of next field */
    }

    return n;
}

(the output is the same)

Look things over and let me know if you have further questions.

How to convert a comma separated string field to array in mongodb

Considering the amount of data, I would definitely run this directly on the server. Here is an example that works to use as a guide. It will replace the names field with a new array from the $split.

db.collectionName.aggregate(
    [
        { "$addFields": { 
            "names": { "$split": [ "$names", "," ] } 
        }},
        {$out:"collectionName"}
    ]
)

---

Related Topics