How to Split a String into Only Two Parts, by the Last Occurrence of the Split Char

How to split a string into only two parts, by the last occurrence of the split char?

String#rpartition, e.g.

irb(main):068:0> str = "Angry Birds 2.4.1"
=> "Angry Birds 2.4.1"
irb(main):069:0> str.rpartition(' ')
=> ["Angry Birds", " ", "2.4.1"]

Since the returned value is an array, using .first and .last would allow to treat the result as if it was split in two, e.g

irb(main):073:0> str.rpartition(' ').first
=> "Angry Birds"
irb(main):074:0> str.rpartition(' ').last
=> "2.4.1"

Splitting on last delimiter in Python string?

Use .rsplit() or .rpartition() instead:

s.rsplit(',', 1)
s.rpartition(',')

str.rsplit() lets you specify how many times to split, while str.rpartition() only splits once but always returns a fixed number of elements (prefix, delimiter & postfix) and is faster for the single split case.

Demo:

>>> s = "a,b,c,d"
>>> s.rsplit(',', 1)
['a,b,c', 'd']
>>> s.rsplit(',', 2)
['a,b', 'c', 'd']
>>> s.rpartition(',')
('a,b,c', ',', 'd')

Both methods start splitting from the right-hand-side of the string; by giving str.rsplit() a maximum as the second argument, you get to split just the right-hand-most occurrences.

If you only need the last element, but there is a chance that the delimiter is not present in the input string or is the very last character in the input, use the following expressions:

# last element, or the original if no `,` is present or is the last character
s.rsplit(',', 1)[-1] or s
s.rpartition(',')[-1] or s

If you need the delimiter gone even when it is the last character, I'd use:

def last(string, delimiter):
    """Return the last element from string, after the delimiter

    If string ends in the delimiter or the delimiter is absent,
    returns the original string without the delimiter.

    """
    prefix, delim, last = string.rpartition(delimiter)
    return last if (delim and last) else prefix

This uses the fact that string.rpartition() returns the delimiter as the second argument only if it was present, and an empty string otherwise.

Split string into two parts only

You could use a,b = split(' ', 1).

The second argument 1 is the maximum number of splits that would be done.

s = 'abcd efgh hijk'
a,b = s.split(' ', 1)
print(a) #abcd
print(b) #efgh hijk

For more information on the string split function, see str.split in the manual.

How to split a string into 2 at the last occurrence of an underscore character

You can use lastIndexOf on String which returns you the index of the last occurrence of a chain of caracters.

String thing = "132131_12313_1321_312";
int index = thing.lastIndexOf("_");
String yourCuttedString = thing.substring(0, index);

It returns -1 if the occurrence is not found in the String.

Split string on the last occurrence of some character

It might be easier to just assume that files which end with a dot followed by alphanumeric characters have extensions.

int p=filePath.lastIndexOf(".");
String e=filePath.substring(p+1);
if( p==-1 || !e.matches("\\w+") ){/* file has no extension */}
else{ /* file has extension e */ }

See the Java docs for regular expression patterns. Remember to escape the backslash because the pattern string needs the backslash.

Best way to split string by last occurrence of character?

Updated Answer (for C# 8 and above)

C# 8 introduced a new feature called ranges and indices, which offer a more concise syntax for working with strings.

string s = "My. name. is Bond._James Bond!";
int idx = s.LastIndexOf('.');

if (idx != -1)
{
    Console.WriteLine(s[..idx]); // "My. name. is Bond"
    Console.WriteLine(s[(idx + 1)..]); // "_James Bond!"
}

Original Answer (for C# 7 and below)

This is the original answer that uses the string.Substring(int, int) method. It's still OK to use this method if you prefer.

string s = "My. name. is Bond._James Bond!";
int idx = s.LastIndexOf('.');

if (idx != -1)
{
    Console.WriteLine(s.Substring(0, idx)); // "My. name. is Bond"
    Console.WriteLine(s.Substring(idx + 1)); // "_James Bond!"
}

split string in to 2 based on last occurrence of a separator

Use rpartition(s). It does exactly that.

You can also use rsplit(s, 1).

How do I Split string only at last occurrence of special character and use both sides after split

You can use String.Substring with String.LastIndexOf:

string str = "SQL injection - Wikipedia, the free encyclopedia - Mozilla Firefox";
int lastIndex = str.LastIndexOf('-');
if (lastIndex + 1 < str.Length)
{
    string firstPart = str.Substring(0, lastIndex);
    string secondPart = str.Substring(lastIndex + 1);
}

Create a extension method (or a simple method) to perform that operation and also add some error checking for lastIndex.

EDIT:

If you want to split on " - " (space-space) then use following to calculate lastIndex

string str = "FirstPart - Mozzila Firefox-somethingWithoutSpace";
string delimiter = " - ";
int lastIndex = str.LastIndexOf(delimiter);
if (lastIndex + delimiter.Length < str.Length)
{
    string firstPart = str.Substring(0, lastIndex);
    string secondPart = str.Substring(lastIndex + delimiter.Length);
}

So for string like:

"FirstPart - Mozzila Firefox-somethingWithoutSpace"

Output would be:

FirstPart 
Mozzila Firefox-somethingWithoutSpace