Match characters of two strings

Question

Suppose,i have two strings.NameIs and Nam.Now i can check if one string is as same as the other using :

If (string1 == string2)

But it won't work here as the strings are not the same.But a portion of it is same.What i am trying to achieve is to check if my main string has any portion of the string given...I came across String.StartWith and EndWith methods but there,i need to specify what the string might start or end with but i cannot as the strings can be anything(that's why at the beginning,i said "Suppose").

So my first question is how to achieve this ? I don't want any step=to=step instruction but atleast a little bit of direction :)

However,if i get past that,there's still a drawback and it is the Case-Sensitive issue.I've come across this but i can't seem to figure the required implementation of this in my case because i need to overcome the first issue first.

How should i achieve these ?

Use .Contains(), its a string function which returns true if main string "contains" the substring — Ryan Wilson, Mar 27 '18 at 19:28
[This question](https://stackoverflow.com/questions/444798/case-insensitive-containsstring) might actually be a better duplicate — maccettura, Mar 27 '18 at 19:43

score 3 · Answer 1 · 2018-03-27T19:44:53.387

3

For ordinal comparison you can use

str1.Contains(str2);

If you need your comparison to be case-insensitive you can do

str1.IndexOf(str2, StringComparison.OrdinalIgnoreCase) >= 0;

Note that you can hide the latter in an extension method, like

static bool ContainsIgnoreCase(this string @this, string other)
    => @this.IndexOf(other, StringComparison.OrdinalIgnoreCase) >= 0;

edited Mar 27 '18 at 19:44

answered Mar 27 '18 at 19:28

The OP stated 2 problems.Your solution get's rid of the first one somewhat.However,there's no explanation in your answer.Please edit it accordingly :) – Software Dev Mar 27 '18 at 19:31
Now,u deserve an upvote :) – Software Dev Mar 27 '18 at 20:17

Woodrow · Accepted Answer · 2018-03-27T19:42:47.533

0

Use String.Contains

if (stringValue.ToLower().Contains(anotherString.ToLower())) {  
    // Do Work // 
}

Just remember to check that strings aren't null when doing contains comparing, or you will get an ArgumentNullException..

edited Mar 27 '18 at 19:42

answered Mar 27 '18 at 19:29

Woodrow

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There are better ways to do case intensive checks than using `ToLower` or `ToUpper`. It works for most character sets, but some languages have letters that don't have 1-to-1 mappings from lower to upper case. – juharr Mar 27 '18 at 19:47

eocron · Answer 3 · 2018-03-27T19:32:49.407

0

Easiest way is this:

a = a?.ToLowerInvariant();
b = b?.ToLowerInvariant();

if(a==null || b==null || a.Contains(b) || b.Contains(a))
{
    //do stuff
}

Why null propogates into true? Because if any variable is null it will definitly contains in other variable. The other two specs is just for non-null entries.

edited Mar 27 '18 at 19:32

answered Mar 27 '18 at 19:30

eocron

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It doesn't get rid of the `case-sensitive` issue,does it ? – Software Dev Mar 27 '18 at 19:32
Now it does. I fixed example. It will ignore case, culture and correctly process null entries. – eocron Mar 27 '18 at 19:36
1

Personally I'd see `null` as unknown. Does a string contain an unknown value? That would be unknown and personally I'd go with it being false, not true. – juharr Mar 27 '18 at 19:44
@juharr Or even throw an argument null exception – Blake Thingstad Mar 27 '18 at 19:45

score 0 · Answer 4 · answered Mar 27 '18 at 19:30

To check if substring is contained in main string, and to ignore case-sensitivity do this, its a boolean function that takes two string parameters:

public bool DoesStringExistInsideMainString(string mainString, string subString)
{
    return mainString.ToLower().Contains(subString.ToLower());

}

Match characters of two strings

4 Answers4