CODEWITHSUNDEEP
c#c++linq
edgarmtze
edgarmtze

Reputation: 25058

C# equivalent of C++ std::string find

I'm looking for the equialent of c++ std::string's find in c#

So in c++ you can have:

string s, nucleo = "ATGC";
s = "TCCCTCCATGCAG";
for (int i = 0; i < (int) s.length(); i++) {
      v = append(v, nucleo.find(s[i]));
      ...
}

How would nucleo.find in linq or loop would look like?

I currently have

int? found = s.find(nucleo);

public static int? find(this string source, string what)
{
    if (source == null) throw new ArgumentNullException("source");
    if (what == null) throw new ArgumentNullException("what");
    if (source.Length == 0) return null;
    if (what.Length == 0) return 0;
    for (int i = 0; i < source.Length; i++)
    {
        if (source.IndexOf(source[i]) == -1) return i;
    }
    return null;
}

Upvotes: 0

Views: 2760

Answers (2)

Dai
Dai

Reputation: 155543

Your C# code makes no sense - it looks like you're re-implenting String.IndexOf yourself when all you need to do is call it directly.

C++'s std::string::find returns the position (i.e. character-index) of the first character of the first match (after the optional start position parameter), this is identical behaviour to .NET's String.IndexOf method. The only difference being that find returns npos on no-match but IndexOf returns -1.

Simply do this (if you want to use null as a value for no-match):

Int32? found = s.IndexOf( nucleo );
if( found == -1 ) found = null;

Upvotes: 1

Dot_NET Pro
Dot_NET Pro

Reputation: 2123

using System;

class Program
{
static void Main()
{
// The input string.
const string value = "Your dog is cute.";

// Test with IndexOf method.
if (value.IndexOf("dog") != -1)
{
    Console.WriteLine("string contains dog!");
}
}
}

Or may be you can use Contains

string s1 = "The quick brown fox jumps over the lazy dog";
string s2 = "fox";
bool b;
b = s1.Contains(s2);
Console.WriteLine("Is the string, s2, in the string, s1?: {0}", b);

Upvotes: 2

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