Searches a string for an instance of a repeated character from specified startIndex. - CSharp System

CSharp examples for System:Char

  1. HOME
  2. CSharp
  3. System
  4. Char

Description

Searches a string for an instance of a repeated character from specified startIndex.

Demo Code

//  Copyright ? 2011, Grid Protection Alliance.  All Rights Reserved.
using System.Text.RegularExpressions;
using System.Text;
using System.IO;//  www.  ja v  a  2 s  .c  o m
using System.Globalization;
using System.ComponentModel;
using System.Collections.Generic;
using System;

public class Main{
        /// <summary>
        /// Searches a string for an instance of a repeated character from specified <paramref name="startIndex"/>.
        /// </summary>
        /// <param name="value">The string to process.</param>
        /// <param name="startIndex">The index from which to begin the search.</param>
        /// <returns>The index of the first instance of any character that is repeated or (-1) if no repeated chars found.</returns>
        public static int IndexOfRepeatedChar(this string value, int startIndex)
        {
            if (string.IsNullOrEmpty(value))
                return -1;

            if (startIndex < 0)
                return -1;

            char c = (char)0;

            for (int i = startIndex; i < value.Length; i++)
            {
                if (value[i] != c)
                    c = value[i];
                else
                {
                    //at least one repeating character
                    return i - 1;
                }
            }
            return -1;
        }
        /// <summary>
        /// Searches a string for an instance of a repeated character.
        /// </summary>
        /// <param name="value">The string to process.</param>
        /// <returns>The index of the first instance of any character that is repeated or (-1) if no repeated chars found.</returns>
        public static int IndexOfRepeatedChar(this string value)
        {
            return IndexOfRepeatedChar(value, 0);
        }
        /// <summary>
        /// Searches a string for a repeated instance of the specified <paramref name="characterToFind"/>.
        /// </summary>
        /// <param name="value">The string to process.</param>
        /// <param name="characterToFind">The character of interest.</param>
        /// <returns>The index of the first instance of the character that is repeated or (-1) if no repeated chars found.</returns>
        public static int IndexOfRepeatedChar(this string value, char characterToFind)
        {
            return IndexOfRepeatedChar(value, characterToFind, 0);
        }
        /// <summary>
        /// Searches a string for a repeated instance of the specified <paramref name="characterToFind"/> from specified <paramref name="startIndex"/>.
        /// </summary>
        /// <param name="value">The string to process.</param>
        /// <param name="characterToFind">The character of interest.</param>
        /// <param name="startIndex">The index from which to begin the search.</param>
        /// <returns>The index of the first instance of the character that is repeated or (-1) if no repeated chars found.</returns>
        public static int IndexOfRepeatedChar(this string value, char characterToFind, int startIndex)
        {
            if (string.IsNullOrEmpty(value))
                return -1;

            if (startIndex < 0)
                return -1;

            if (characterToFind == 0)
                return -1;

            char c = (char)0;

            for (int i = startIndex; i < value.Length; i++)
            {
                if (value[i] == characterToFind)
                {
                    if (value[i] != c)
                        c = value[i];
                    else
                    {
                        //at least one repeating character
                        return i - 1;
                    }
                }
                else
                    c = (char)0;
            }

            return -1;
        }
}

Related Tutorials