How to determine if string contains specific substring within the first X characters

Question

I want to check whether Value1 below contains "abc" within the first X characters. How would you check this with an if statement?

var Value1 = "ddabcgghh";

if (Value1.Contains("abc"))
{
    found = true;
}

It could be within the first 3, 4 or 5 characters.

Answer 1

Or if you need to set the value of found:

found = Value1.StartsWith("abc")

Edit: Given your edit, I would do something like:

found = Value1.Substring(0, 5).Contains("abc")

Answer 2

我会使用IndexOf方法的一个重载

bool found = Value1.IndexOf("abc", 0, 7) != -1;

Answer 3

shorter version:

found = Value1.StartsWith("abc");

sorry, but I am a stickler for 'less' code.

---

Given the edit of the questioner I would actually go with something that accepted an offset, this may in fact be a Great place to an Extension method that overloads StartsWith

public static class StackOverflowExtensions
{
    public static bool StartsWith(this String val, string findString, int count)
    {
        return val.Substring(0, count).Contains(findString);
    }
}

Answer 4

if (Value1.StartsWith("abc")) { found = true; }

Answer 5

Use IndexOf is easier and high performance.

int index = Value1.IndexOf("abc");
bool found = index >= 0 && index < x;

Answer 6

This is what you need :

if (Value1.StartsWith("abc"))
{
found = true;
}

Answer 7

你很接近......但是使用： if (Value1.StartsWith("abc"))

Answer 8

A more explicit version is

found = Value1.StartsWith("abc", StringComparison.Ordinal);

It's best to always explicitly list the particular comparison you are doing. The String class can be somewhat inconsistent with the type of comparisons that are used.

Answer 9

You can also use regular expressions (less readable though)

string regex = "^.{0,7}abc";

System.Text.RegularExpressions.Regex reg = new System.Text.RegularExpressions.Regex(regex);
string Value1 = "sssddabcgghh";

Console.WriteLine(reg.Match(Value1).Success);

Answer 10

Adding on from the answer below i have created this method:

    public static bool ContainsInvalidStrings(IList<string> invalidStrings,string stringToCheck)
    {

        foreach (string invalidString in invalidStrings)
        {
            var index = stringToCheck.IndexOf(invalidString, StringComparison.InvariantCultureIgnoreCase);
            if (index != -1)
            {
                return true;
            }
        }
        return false;
    }

it can be used like this:

            var unsupportedTypes = new List<string>()
        {
            "POINT Empty",
            "MULTIPOINT",
            "MULTILINESTRING",
            "MULTIPOLYGON",
            "GEOMETRYCOLLECTION",
            "CIRCULARSTRING",
            "COMPOUNDCURVE",
            "CURVEPOLYGON",
            "MULTICURVE",
            "TRIANGLE",
            "TIN",
            "POLYHEDRALSURFACE"
        };


            bool hasInvalidValues =   ContainsInvalidStrings(unsupportedTypes,possibleWKT);

you can check for multiple invalid values this way.