Add String into existing String whenever specific characters found

Question

I want to add a specific String into an existing String whenever the existing String contains one of the following characters: =, +, -, * or /.

For example, I want to add the String "test" into this existing String: "=ABC+DEF"

Resulting String should be: "=testABC+testDEF"

My first version looks like this and I quess it works but code is ugly

string originalFormula;
string newFormula1 = originalFormula.Replace("=", "=test");
string newFormula2 = newFormula1.Replace("+", "+test");
string newFormula3 = newFormula2 .Replace("-", "-test");
string newFormula4 = newFormula3 .Replace("*", "*test");
string newFormula5 = newFormula4 .Replace("/", "/test");

Is there some shorter way to achive it ?

If that works you should use it. You will definitely not find anything shorter, more efficient or more readable. — Tim Schmelter, Jun 26 '17 at 09:05
Because `Replace` returns the updated string, you could just chain each `Replace` call: `string newFormula = originalFormula.Replace("=", "=test").Replace("+", "+test").Replace("-", "-test").Replace("*", "*test").Replace("/", "/test");` - I don't know if it makes it more readable though. — Matt Hogan-Jones, Jun 26 '17 at 09:09
Alternatively, this question shows how to use a dictionary of search-replace pairs that might be helpful - https://stackoverflow.com/questions/1231768/c-sharp-string-replace-with-dictionary — Matt Hogan-Jones, Jun 26 '17 at 09:10
@TimSchmelter I will say that it is more readable (lol, semi-irony)... The regex is `"[=+*/-]"`, the replacement is `"$$test"`... See http://regexstorm.net/tester?p=%5b%3d%2b*%2f-%5d&i=%3dABC%2bDEF&r=%24%24test . — xanatos, Jun 26 '17 at 09:10
What if the string is `" = 123 + 456"` shall we consider *spaces* or not? — Dmitry Bychenko, Jun 26 '17 at 09:14
Yet another question: `"t == --abc"` what is the desired result? `x = -1.2e+123`? — Dmitry Bychenko, Jun 26 '17 at 09:22
I'm voting to close this question as off-topic because OP tries to improve working code(it's even unclear why he needs to improve it) — Tim Schmelter, Jun 26 '17 at 09:23
@TimSchmelter, I feel you are both wrong to claim the code couldn't be made simpler (Philipp's simple use of a regex shows it can be) and wrong to vote to close it. — David Arno, Jun 26 '17 at 10:12

score 5 · Accepted Answer · answered Jun 26 '17 at 09:35

If you want your code a bit more elegant, go with Regex.

using System.Text.RegularExpressions;

string originalFormula = ...;
var replacedString = Regex.Replace(myString, "[-+*/=]", "$&test");

For better understanding: [-+*/=] groups the charackters you want to check the string for. $&test Replaces the found charackter with its match ($&) and adds test to it.

Ortund · Answer 2 · 2017-06-26T09:30:54.827

-1

If your problem is that your code looks ugly maybe you could rewrite it to use a list rather...

List<char> characters = new List<char> { '+', '-', '*', '/' };

foreach (var c in characters)
{
    string newValue = String.Format("{0}{1}", c, somethingElse);
    if (originalForumla.Contains(c);
    {
        newForumla = originalFormula.Replace(c, newValue);
    }
}

edited Jun 26 '17 at 09:30

answered Jun 26 '17 at 09:24

Ortund

8,095
18
71
139

Add String into existing String whenever specific characters found

2 Answers2