如何检查两个字符串的长度相同？

Question

I want to check if two string are of the same length. I tried the following, but it doesn't work.

string passnew = "1233";
string passcnfrm = "1234";

if((passnew.Length&&passcnfrm.Length)>6 ||(passnew.Length&&passcnfrm.Length)<15)
{ 
    // ...
}

Why does it not work? What do I need to change?

Answer 1

if(passnew.Length == passcnfrm.Length && 
   passnew.Length > 6 && passnew.Length < 15)
{
    // do stuff
}

Answer 2

You are missing some basic syntax lessons. What you write inside of these brackets are conditions. We have unary operators (operating on one thing), binary operators (two) and one tertiary operator (forget about that one).

You cannot construct something like your "boundary test" with those easily.

A possible way:

(passnew.Length > 6) && (passcnfrm.Length > 6)

But you aren't testing if the length is equal anyway, even if you could use a syntax like that. You seem to want to compare if both are longer than 6 chars and shorter than 15 chars. One at 7 and one at 14 would satisfy both conditions..

Answer 3

if(passnew.Length == passcnfrm.Length && 
   (passnew.Length < 15 && passnew.Length > 6))
{ 
    // ...
}

Checks both are same length, and either one is more than 6 and less than 15 characters long.

Answer 4

that would be:

if(passcnfrm.Length.Equals(passnew.Length))
 {
   //do stuff
 }

Answer 5

A probably better way to do it is:

if (( passnew != null && passcnfrm != null )
    ( passnew == passcnfrm )
&&  ( passnew.Length > 6 && passnew.Length < 15 ))
{
    // do stuff
}

Hides the length check inside the equality check which you'll probably need, it isn't in your question but the variable names make it pretty clear you're doing a password change function there. I added the null check to make sure the length checks don't throw a NullReferenceException, not needed in the example because you assign both manually, but might save some trouble if you're going to convert this to a method later on.

Answer 6

You can use like this: if (s.Contains(s1[i]))

or:

boolean equalsIgnoreCase(String anotherString);

or use this method:

public static int occurrence(string [] a, string a2) { int occ = 0; for (int i = 0; i < a.Length;i++ ) { if(a[i].Equals(a2)) { occ++; }

        }
        return occ;
    }