c# contains part of string
32,068
Solution 1
"some string".Contains("str") will return true, are you having problems with case sesitivity?
If so you could use this:
public static bool Contains(this string source, string toCheck, StringComparison comp) {
return source.IndexOf(toCheck, comp) >= 0;
}
string title = "STRING";
bool contains = title.Contains("string", StringComparison.OrdinalIgnoreCase);
(Taken from Case insensitive 'Contains(string)')
Solution 2
Use IndexOf
string searchWithinThis = "ABCDEFGHIJKLMNOP";
string searchForThis = "DEF";
int firstCharacter = searchWithinThis.IndexOf(searchForThis);
Console.WriteLine("First occurrence: {0}", firstCharacter);
if substring is not found, it returns -1. Its very useful for also knowing where abouts the string is found.
Solution 3
For shits and giggles I thought it was a nice lunch-break project to come up with a simple, but 'elegant' solution to the Question (as I understood it :)):
E.g.
// I made up a Material class for testing:
public class Materiel
{
public string A { get; set; }
public int B { get; set; }
public DateTime? C { get; set; }
public string D { get; set; }
public Nested E { get; set; }
}
// [...] usage:
foreach (var pattern in new[]{ "World" , "dick", "Dick", "ick", "2012", "Attach" })
Console.WriteLine("{0} records match '{1}'", Database.Search(pattern).Count(), pattern);
Outputs:
2 records match 'World'
1 records match 'dick'
1 records match 'Dick'
2 records match 'ick'
1 records match '2012'
2 records match 'Attach'
The code also supports
- regex matches
- any property types (e.g. nullable DateTimes or nested classes)
- showing which property matched the pattern/substring
Enjoy:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;
namespace AClient
{
public class Materiel
{
public string A { get; set; }
public int B { get; set; }
public DateTime? C { get; set; }
public string D { get; set; }
public Nested E { get; set; }
}
public struct Nested
{
public string Data { get; set; }
public override string ToString() { return string.Format("Extra: {0}", Data); }
}
public static class FullText
{
public class PropMatched<T> { public PropertyInfo Property; public T Item; }
public static IEnumerable<PropMatched<T> > ByProperty<T>(this IEnumerable<T> items, string substr)
{
return items.ByProperty(new Regex(Regex.Escape(substr), RegexOptions.IgnoreCase));
}
public static IEnumerable<PropMatched<T> > ByProperty<T>(this IEnumerable<T> items, Regex pattern)
{
return items.Select(i => i.MatchingProperties(pattern)).Where(m => null != m);
}
public static IEnumerable<T> Search<T>(this IEnumerable<T> items, string substr)
{
return items.Search(new Regex(Regex.Escape(substr), RegexOptions.IgnoreCase));
}
public static IEnumerable<T> Search<T>(this IEnumerable<T> items, Regex pattern)
{
return items.Where(i => null != i.MatchingProperties(pattern));
}
public static PropMatched<T> MatchingProperties<T>(this T item, Regex pattern)
{
if (null == pattern || null == item) return null;
var properties = item.GetType().GetProperties(BindingFlags.Public | BindingFlags.FlattenHierarchy | BindingFlags.Instance);
var matches = from prop in properties
let val = prop.GetGetMethod(true).Invoke(item, new object[]{})
where pattern.IsMatch((val??"").ToString())
select prop;
var found = matches.FirstOrDefault();
return found == null ? null : new PropMatched<T> {Item = item, Property = found};
}
}
class Client
{
private static readonly IEnumerable<Materiel> Database = new List<Materiel>
{
new Materiel {
A = "Hello", B = 1, C = null, D = "World",
E = new Nested {Data = "Attachment"}
},
new Materiel {
A = "Transfigured", B = 2, C = null, D = "Nights",
E = new Nested {Data = "Schoenberg"}
},
new Materiel {
A = "Moby", B = 3, C = null, D = "Dick",
E = new Nested {Data = "Biographic"}
},
new Materiel {
A = "Prick", B = 4, C = DateTime.Today, D = "World",
E = new Nested {Data = "Attachment"}
},
new Materiel {
A = "Oh Noes", B = 2, C = null, D = "Nights",
E = new Nested {Data = "Schoenberg"}
},
};
static void Main()
{
foreach (var pattern in new[]{ "World" , "dick", "Dick", "ick", "2012", "Attach" })
Console.WriteLine("{0} records match '{1}'", Database.Search(pattern).Count(), pattern);
// regex sample:
var regex = new Regex(@"N\w+s", RegexOptions.IgnoreCase);
Console.WriteLine(@"{0} records match regular expression 'N\w+s'", Database.Search(regex).Count());
// with context info:
foreach (var contextMatch in Database.ByProperty(regex))
{
Console.WriteLine("1 match of regex in propery {0} with value '{1}'",
contextMatch.Property.Name, contextMatch.Property.GetGetMethod().Invoke(contextMatch.Item, new object[0]));
}
}
}
}
Solution 4
class SearchInString
{
static void Main()
{
string strn= "A great things are happen with great humans.";
System.Console.WriteLine("'{0}'",strn);
bool case1= strn.StartsWith("A great");
System.Console.WriteLine("starts with 'A great'? {0}", case1);
bool case2= strn.StartsWith("A great", System.StringComparison.OrdinalIgnoreCase);
System.Console.WriteLine("starts with 'A great'? {0} (ignoring case)", case2);
bool case3= strn.EndsWith(".");
System.Console.WriteLine("ends with '.'? {0}", case3);
int start= strn.IndexOf("great");
int end= strn.LastIndexOf("great");
string strn2 = strn.Substring(start, end- start);
System.Console.WriteLine("between two 'great' words: '{0}'", strn2);
}
}
Author by
raze
Updated on March 30, 2020Comments
-
raze about 4 years
So I have a list with Materiel-objects. In Materiel I have 15 get and set methods. I want to construct a search-method that loops all the objects in the list, and all of the variables in each Materiel-object. The looping part is easy enough, but I'm struggling with the string-contains-part. The search term could for instance be "acto", and I should get a hit for "Tractor". I have tried using the string-Contains class, but as far as I can figure out, it only checks the string beginning in position 0. So "Tra" gets a hit, but not "acto".
Is there any build in classes, or should I program one myself?
Sorry for the bad explanation.
My code. I see now that I get hits for the substring, but also other results :)
protected void Button_search_Click(object sender, EventArgs e) { string searchTerm = TextBox1.Text.ToString().ToLower(); TableRow row; TableCell cell; int rowNumber = 1; foreach (Materiell mat in allItems) { if (searchTerm.Contains(mat.itemID.ToString().ToLower()) || searchTerm.Contains(mat.manufacturer.ToLower()) || searchTerm.Contains(mat.model.ToLower()) || searchTerm.Contains(mat.serialNo.ToLower()) || searchTerm.Contains(mat.dateProd.ToString().ToLower()) || searchTerm.Contains(mat.location.ToLower()) || searchTerm.Contains(mat.mainCategory.ToLower()) || searchTerm.Contains(mat.subCategory.ToLower()) || searchTerm.Contains(mat.dateAcquired.ToString().ToLower()) || searchTerm.Contains(mat.price.ToString().ToLower()) || searchTerm.Contains(mat.ownerID.ToString().ToLower()) || searchTerm.Contains(mat.extra.ToString().ToLower()) || searchTerm.Contains(mat.textComment.ToLower()) || searchTerm.Contains(mat.active.ToString().ToLower())) { row = new TableRow(); row.ID = "row" + rowNumber.ToString(); rowNumber++; cell = new TableCell(); cell.Text = "<a href=\"#\" class=\"opendiv\">" + mat.itemID.ToString() + "</a>"; row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.manufacturer.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.model.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.serialNo.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.dateProd.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.location.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.mainCategory.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.subCategory.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.dateAcquired.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.price.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.ownerID.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.extra.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.ownDefData.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.textComment.ToString(); row.Cells.Add(cell); cell = new TableCell(); cell.Text = mat.active.ToString(); row.Cells.Add(cell); Table1.Rows.Add(row); } } } -
LexyStardust about 12 yearsNeat little extension method. Consider that one stolen!
-
Guffa about 12 yearsRight... The
IndexOfmethod has aStringComparisonmethod that theContainsmethod lacks, didn't think of that. That's better than usingToUpperbefore checking. Instantly incorporated into the project that I am currently working on. :) -
Guffa about 12 yearsActually he already does. The
String.Containsmethod just callsIndexOf. -
sehe about 12 yearsOMG. Surprisingly, this was accepted as the answer. Well, in case you wanted a fulltext search indeed, see here: stackoverflow.com/questions/9923158/…
