Get the String Up to a Specific Character

Get Substring - everything before certain char

.Net Fiddle example

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("223232-1.jpg".GetUntilOrEmpty());
        Console.WriteLine("443-2.jpg".GetUntilOrEmpty());
        Console.WriteLine("34443553-5.jpg".GetUntilOrEmpty());

        Console.ReadKey();
    }
}

static class Helper
{
    public static string GetUntilOrEmpty(this string text, string stopAt = "-")
    {
        if (!String.IsNullOrWhiteSpace(text))
        {
            int charLocation = text.IndexOf(stopAt, StringComparison.Ordinal);

            if (charLocation > 0)
            {
                return text.Substring(0, charLocation);
            }
        }

        return String.Empty;
    }
}

Results:

In java how to get substring from a string till a character c?

look at String.indexOf and String.substring.

Make sure you check for -1 for indexOf.

Get the string up to a specific character

Expanding on @appzYourLife answer, the following will also trim off the whitespace characters after removing everything after the @ symbol.

import Foundation

var str = "hello, how are you @tom"

if str.contains("@") {
    let endIndex = str.range(of: "@")!.lowerBound
    str = str.substring(to: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)
}
print(str) // Output - "hello, how are you"

UPDATE:

In response to finding the last occurance of the @ symbol in the string and removing it, here is how I would approach it:

var str = "hello, how are you @tom @tim?"
if str.contains("@") {
    //Reverse the string
    var reversedStr = String(str.characters.reversed())
    //Find the first (last) occurance of @
    let endIndex = reversedStr.range(of: "@")!.upperBound
    //Get the string up to and after the @ symbol
    let newStr = reversedStr.substring(from: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)

    //Store the new string over the original
    str = String(newStr.characters.reversed())
    //str = "hello, how are you @tom"
}

Or looking at @appzYourLife answer use range(of:options:range:locale:) instead of literally reversing the characters

var str = "hello, how are you @tom @tim?"
if str.contains("@") {
    //Find the last occurrence of @
    let endIndex = str.range(of: "@", options: .backwards, range: nil, locale: nil)!.lowerBound
    //Get the string up to and after the @ symbol
    let newStr = str.substring(from: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)

    //Store the new string over the original
    str = newStr
    //str = "hello, how are you @tom"
}

As an added bonus, here is how I would approach removing every @ starting with the last and working forward:

var str = "hello, how are you @tom and @tim?"
if str.contains("@") {

    while str.contains("@") {
        //Reverse the string
        var reversedStr = String(str.characters.reversed())
        //Find the first (last) occurance of @
        let endIndex = reversedStr.range(of: "@")!.upperBound
        //Get the string up to and after the @ symbol
        let newStr = reversedStr.substring(from: endIndex).trimmingCharacters(in: .whitespacesAndNewlines)

        //Store the new string over the original
        str = String(newStr.characters.reversed())
    }
    //after while loop, str = "hello, how are you"
}

Get the beginning of a string until a given char

What about using strtok and "[" as a delimiter?

#include <string.h> /* for strtok */
#include <stdio.h>  /* for printf */
int main()
{
    char str[] = "M1[r2][r3]"; // str will be modified by strtok
    const char deli[] = "[";   // deli could also be declared as [2] or as const char *. Take your pick...
    char *token;

    token = strtok(str, deli); // can also call strtok(str, "["); and not use variable deli at all
    printf("%s", token);       // printf("%s", str); will print the same result

    /* OUTPUT: M1 */

    return 0;    
}

How would I get everything before a : in a string Python

Just use the split function. It returns a list, so you can keep the first element:

>>> s1.split(':')
['Username', ' How are you today?']
>>> s1.split(':')[0]
'Username'

Java: Getting a substring from a string starting after a particular character

String example = "/abc/def/ghfj.doc";
System.out.println(example.substring(example.lastIndexOf("/") + 1));

Select all characters in a string until a specific character Ruby

You can avoid creating an unnecessary Array (like Array#split) or using a Regex (like Array#gsub) by using.

a = "2.452811139617034,42.10874821716908|3.132087902867818,42.028314077306646|-0.07934861041448178,41.647538468746916|-0.07948265046522918,41.64754863599606"

a[0,a.index('|')]
#=>"2.452811139617034,42.1087482171"

This means select characters at positions 0 up to the index of the first pipe (|). Technically speaking it is start at position 0 and select the length of n where n is the index of the pipe character which works in this case because ruby uses 0 based indexing.

As @CarySwoveland astutely pointed out the string may not contain a pipe in which case my solution would need to change to

#to return entire string
a[0,a.index('|') || a.size]
# or
b = a.index(?|) ? a[0,b] : a
# or to return empty string
a[0,a.index('|').to_i]
# or to return nil
a[0,a.index(?|) || -1]

How to get a string after specific character and before specific character in MySQL?

Using the base string function SUBSTRING_INDEX we can try:

SELECT
    SUBSTRING_INDEX(
        SUBSTRING_INDEX('lipnice sivá <(Poa glauca)>', '<(', -1), ')>', 1);

If you are using MySQL 8+, then we can REGEXP_REPLACE for a regex based solution:

SELECT
    REGEXP_REPLACE('lipnice sivá <(Poa glauca)>', '^.*<\\((.*?)\\)>.*$', '$1');

Follow the demo link below to see both queries.

Demo

How to get specific character in a string?

You really should clarify the issue you're having; feel free to read How to Ask.

Basic Loop

As far as your question states (from my understanding), you would like to repeatidly call a method and have that method return the index of a string that corresponds to the current call. I would look into the for loop and string.Substring(int), you could also just access the string as a char array (which I do below).

static void Main() {
    string myString = "SomeStringData";
    for (int i = 0; i < myString.Length; i++)
        Console.Write(GetCharacter(myString, i));
}
static char GetCharacter(string data, int index) => data[index];

The code above can be modified to make sequential calls until you need to stop looping which will meet your condition of the first index being returned once the end of the string has been reached:

string myString = "abc";
for (int i = 0; i < myString.Length; i++) {
    Console.Write(GetCharacter(myString, i);

    // This will reset the loop to make sequential calls.
    if (i == myString.Length)
        i = 0;
}

If you wish to escape the loop above, you'll need to add some conditional logic to determine if the loop should be broken, or instead of looping, just make individual calls to the GetCharacter(string, int) method supplied. Also, you should only modify the iteration variable i if you truly need to; in this case you could switch to a while loop which would be more appropriate:

string myString = "abc";
string response = string.Empty;
int index = 0;
while (response.TrimEnd().ToUpper() != "END") {
    Console.WriteLine(GetCharacter(myString, index++));
    Console.WriteLine("If you wish to end the test please enter 'END'.");
    response = Console.ReadLine();

    if (index > myString.Length)
        index = 0;
}

Get Character (Expression Body vs Full Body)

C# 6 introduced the ability to write methods as expressions; a method written as an expression is called an Expression-Bodied-Member. For example, the two methods below function in the exact same manner:

static char GetCharacter(string data, int index) => data[index];
static char GetCharacter(string data, int index) {
    return data[index];
}

Expression body definitions let you provide a member's implementation in a very concise, readable form. You can use an expression body definition whenever the logic for any supported member, such as a method or property, consists of a single expression.