How to not include line breaks when comparing two strings.

Question

i am comparing updates to two strings. i did a:

 string1 != string2

and they turn out different. I put them in the "Add Watch" and i see the only difference is one has line breaks and the other doesnt'.:

 string1 = "This is a test. \nThis is a test";
 string2 = "This is a test. This is a test";

i basically want to do a compare but dont include line breaks. So if line break is the only difference then consider them equal.

Answer 1

string1.replace('\n','') != string2.replace('\n','')

Answer 2

Cant you just strip out the line breaks before comparing the strings?

E.g. (pseudocode)...

string1.replace('\n','') != string2.replace('\n','')

Answer 3

A quick and dirty way, when performance isn't much of an issue:

string1.Replace("\n", "") != string2.Replace("\n", "")

Answer 4

I'd suggest regex to reduce every space, tab, \r, \n to a single space :

Regex.Replace(string1, @"\s+", " ") != Regex.Replace(string2, @"\s+", " ")

Answer 5

Assuming:

1. The sort of direct char-value-for-char-value comparison of != and == is what is wanted here, except for the matter of newlines.
2. The strings are, or may, be large enough or compared often enough to make just replacing "\n" with an empty string too inefficient.

Then:

public bool LinelessEquals(string x, string y)
{
    //deal with quickly handlable cases quickly.
    if(ReferenceEquals(x, y))//same instance
        return true;         // - generally happens often in real code,
                             //and is a fast check, so always worth doing first.
    //We already know they aren't both null as
    //ReferenceEquals(null, null) returns true.
    if(x == null || y == null)
        return false;
    IEnumerator<char> eX = x.Where(c => c != '\n').GetEnumerator();
    IEnumerator<char> eY = y.Where(c => c != '\n').GetEnumerator();
    while(eX.MoveNext())
    {
        if(!eY.MoveNext()) //y is shorter
            return false;
        if(ex.Current != ey.Current)
            return false;
    }
    return !ey.MoveNext(); //check if y was longer.
}

This is defined as equality rather than inequality, so you could easily adapt it to be an implementation of IEqualityComparer<string>.Equals. Your question for a linebreak-less string1 != string2 becomes: !LinelessEquals(string1, string2)