Consider the following english phrase
FRIEND AND COLLEAGUE AND (FRIEND OR COLLEAGUE AND (COLLEAGUE AND FRIEND AND FRIEND))
I want to be able to programmatically change arbitrary phrases, such as above, to something like:
SELECT * FROM RelationTable R1 JOIN RelationTable R2 ON R2.RelationName etc etc WHERE
R2.RelationName = FRIEND AND R2.RelationName = Colleague AND (R3.RelationName = FRIENd,
etc. etc.
My question is. How do I take the initial string, strip it of the following words and symbols : AND, OR, (, ),
Then change each word, and create a new string.
I can do most of it, but my main problem is that if I do a string.split and only get the words I care for, I can't really replace them in the original string because I lack their original index. Let me explain in a smaller example:
string input = "A AND (B AND C)"
Split the string for space, parenthesies, etc, gives: A,B,C
input.Replace("A", "MyRandomPhrase")
But there is an A in AND.
So I moved into trying to create a regular expression that matches exact words, post split, and replaces. It started to look like this:
"(\(|\s|\))*" + itemOfInterest + "(\(|\s|\))+"
Am I on the right track or am I overcomplicating things..Thanks !
You can try using Regex.Replace, with \b word boundary regex
string input = "A AND B AND (A OR B AND (B AND A AND A))";
string pattern = "\\bA\\b";
string replacement = "MyRandomPhrase";
Regex rgx = new Regex(pattern);
string result = rgx.Replace(input, replacement);
class Program
{
static void Main(string[] args)
{
string text = "A AND (B AND C)";
List<object> result = ParseBlock(text);
Console.ReadLine();
}
private static List<object> ParseBlock(string text)
{
List<object> result = new List<object>();
int bracketsCount = 0;
int lastIndex = 0;
for (int i = 0; i < text.Length; i++)
{
char c = text[i];
if (c == '(')
bracketsCount++;
else if (c == ')')
bracketsCount--;
if (bracketsCount == 0)
if (c == ' ' || i == text.Length - 1)
{
string substring = text.Substring(lastIndex, i + 1 - lastIndex).Trim();
object itm = substring;
if (substring[0] == '(')
itm = ParseBlock(substring.Substring(1, substring.Length - 2));
result.Add(itm);
lastIndex = i;
}
}
return result;
}
}
How can I capitalize every third letter of a string in C#?
I loop through the whole string with a for loop, but I can't think of the sequence right now.
I suspect you just want something like this:
// String is immutable; copy to a char[] so we can modify that in-place
char[] chars = input.ToCharArray();
for (int i = 0; i < chars.Length; i += 3)
{
chars[i] = char.ToUpper(chars[i]);
}
// Now construct a new String from the modified character array
string output = new string(chars);
That assumes you want to start capitalizing from the first letter, so "abcdefghij" would become "AbcDefGhiJ". If you want to start capitalizing elsewhere, just change the initial value of i.
var s = "Lorem ipsum";
var foo = new string(s
.Select((c, i) => (i + 1) % 3 == 0 ? Char.ToUpper(c) : c)
.ToArray());
You are already looping through the characters inside a string? Then add a counter, increment it on each iteration, and if it is 3, then use .ToUpper(currentCharacter) to make it upper case. Then reset your counter.
You could just use a regular expression.
If the answer is every third char then you want
var input = "sdkgjslgjsklvaswlet";
var regex = new Regex("(..)(.)");
var replacement = regex.Replace(input, delegate(Match m)
{
return m.Groups[1].Value + m.Groups[2].Value.ToUpper();
});
If you want every third character, but starting with the first you want:
var input = "sdkgjslgjsklvaswlet";
var regex = new Regex("(.)(..)");
var replacement = regex.Replace(input, delegate(Match m)
{
return m.Groups[1].Value.ToUpper() + m.Groups[2].Value;
});
If you want a loop, you can convert to a character array first, so you can alter the values.
For every third character:
var x = input.ToCharArray();
for (var i = 2; i <x.Length; i+=3) {
x[i] = char.ToUpper(x[i]);
}
var replacement = new string(x);
For every third character from the beginning:
var x = input.ToCharArray();
for (var i = 0; i <x.Length; i+=3) {
x[i] = char.ToUpper(x[i]);
}
var replacement = new string(x);
What's the easiest and fastest way to find a sub-string(template) in a string and replace it with something else following the template's letter case (if all lower case - replace with lowercase, if all upper case - replace with uppercase, if begins with uppercase and so on...)
so if the substring is in curly braces
"{template}" becomes "replaced content"
"{TEMPLATE}" becomes "REPLACED CONTENT" and
"{Template}" becomes "Replaced content" but
"{tEMPLATE}" becomes "rEPLACED CONTENT"
Well, you could use regular expressions and a match evaluator callback like this:
regex = new Regex(#"\{(?<value>.*?)\}",
RegexOptions.CultureInvariant | RegexOptions.ExplicitCapture);
string replacedText = regex.Replace(<text>,
new MatchEvaluator(this.EvaluateMatchCallback));
And your evaluator callback would do something like this:
private string EvaluateMatchCallback(Match match) {
string templateInsert = match.Groups["value"].Value;
// or whatever
string replacedText = GetReplacementTextBasedOnTemplateValue(templateInsert);
return replacedText;
}
Once you get the regex match value you can just do a case-sensitive comparison and return the correct replacement value.
EDIT I sort of assumed you were trying to find the placeholders in a block of text rather than worry about the casing per se, if your pattern is valid all the time then you can just check the first two characters of the placeholder itself and that will tell you the casing you need to use in the replacement expression:
string foo = "teMPLATE";
if (char.IsLower(foo[0])) {
if (char.IsLower(foo[1])) {
// first lower and second lower
}
else {
// first lower and second upper
}
}
else {
if (char.IsLower(foo[1])) {
// first upper and second lower
}
else {
// first upper and second upper
}
}
I would still use a regular expression to match the replacement placeholder, but that's just me.
You can check the case of the first two letters of the placeholder and choose one of the four case transforming strategies for the inserted text.
public static string Convert(string input, bool firstIsUpper, bool restIsUpper)
{
string firstLetter = input.Substring(0, 1);
firstLetter = firstIsUpper ? firstLetter.ToUpper() : firstLetter.ToLower();
string rest = input.Substring(1);
rest = restIsUpper ? rest.ToUpper() : rest.ToLower();
return firstLetter + rest;
}
public static string Replace(string input, Dictionary<string, string> valueMap)
{
var ms = Regex.Matches(input, "{(\\w+?)}");
int i = 0;
var sb = new StringBuilder();
for (int j = 0; j < ms.Count; j++)
{
string pattern = ms[j].Groups[1].Value;
string key = pattern.ToLower();
bool firstIsUpper = char.IsUpper(pattern[0]);
bool restIsUpper = char.IsUpper(pattern[1]);
sb.Append(input.Substring(i, ms[j].Index - i));
sb.Append(Convert(valueMap[key], firstIsUpper, restIsUpper));
i = ms[j].Index + ms[j].Length;
}
return sb.ToString();
}
public static void DoStuff()
{
Console.WriteLine(Replace("--- {aAA} --- {AAA} --- {Aaa}", new Dictionary<string,string> {{"aaa", "replacement"}}));
}
Ended up doing that:
public static string ReplaceWithTemplate(this string original, string pattern, string replacement)
{
var template = Regex.Match(original, pattern, RegexOptions.IgnoreCase).Value.Remove(0, 1);
template = template.Remove(template.Length - 1);
var chars = new List<char>();
var isLetter = false;
for (int i = 0; i < replacement.Length; i++)
{
if (i < (template.Length)) isLetter = Char.IsUpper(template[i]);
chars.Add(Convert.ToChar(
isLetter ? Char.ToUpper(replacement[i])
: Char.ToLower(replacement[i])));
}
return new string(chars.ToArray());
}
I have a part of a URL like this:
/home/{value1}/something/{anotherValue}
Now i want to replace all between the brackets with values from a string-array.
I tried this RegEx pattern: \{[a-zA-Z_]\} but it doesn't work.
Later (in C#) I want to replace the first match with the first value of the array, second with the second.
Update: The /'s cant be used to separate. Only the placeholders {...} should be replaced.
Example: /home/before{value1}/and/{anotherValue}
String array: {"Tag", "1"}
Result: /home/beforeTag/and/1
I hoped it could works like this:
string input = #"/home/before{value1}/and/{anotherValue}";
string pattern = #"\{[a-zA-Z_]\}";
string[] values = {"Tag", "1"};
MatchCollection mc = Regex.Match(input, pattern);
for(int i, ...)
{
mc.Replace(values[i];
}
string result = mc.GetResult;
Edit:
Thank you Devendra D. Chavan and ipr101,
both solutions are greate!
You can try this code fragment,
// Begin with '{' followed by any number of word like characters and then end with '}'
var pattern = #"{\w*}";
var regex = new Regex(pattern);
var replacementArray = new [] {"abc", "cde", "def"};
var sourceString = #"/home/{value1}/something/{anotherValue}";
var matchCollection = regex.Matches(sourceString);
for (int i = 0; i < matchCollection.Count && i < replacementArray.Length; i++)
{
sourceString = sourceString.Replace(matchCollection[i].Value, replacementArray[i]);
}
[a-zA-Z_] describes a character class. For words, you'll have to add * at the end (any number of characters within a-zA-Z_.
Then, to have 'value1' captured, you'll need to add number support : [a-zA-Z0-9_]*, which can be summarized with: \w*
So try this one : {\w*}
But for replacing in C#, string.Split('/') might be easier as Fredrik proposed. Have a look at this too
You could use a delegate, something like this -
string[] strings = {"dog", "cat"};
int counter = -1;
string input = #"/home/{value1}/something/{anotherValue}";
Regex reg = new Regex(#"\{([a-zA-Z0-9]*)\}");
string result = reg.Replace(input, delegate(Match m) {
counter++;
return "{" + strings[counter] + "}";
});
My two cents:
// input string
string txt = "/home/{value1}/something/{anotherValue}";
// template replacements
string[] str_array = { "one", "two" };
// regex to match a template
Regex regex = new Regex("{[^}]*}");
// replace the first template occurrence for each element in array
foreach (string s in str_array)
{
txt = regex.Replace(txt, s, 1);
}
Console.Write(txt);
I would like to split a string with delimiters but keep the delimiters in the result.
How would I do this in C#?
If the split chars were ,, ., and ;, I'd try:
using System.Text.RegularExpressions;
...
string[] parts = Regex.Split(originalString, #"(?<=[.,;])")
(?<=PATTERN) is positive look-behind for PATTERN. It should match at any place where the preceding text fits PATTERN so there should be a match (and a split) after each occurrence of any of the characters.
If you want the delimiter to be its "own split", you can use Regex.Split e.g.:
string input = "plum-pear";
string pattern = "(-)";
string[] substrings = Regex.Split(input, pattern); // Split on hyphens
foreach (string match in substrings)
{
Console.WriteLine("'{0}'", match);
}
// The method writes the following to the console:
// 'plum'
// '-'
// 'pear'
So if you are looking for splitting a mathematical formula, you can use the following Regex
#"([*()\^\/]|(?<!E)[\+\-])"
This will ensure you can also use constants like 1E-02 and avoid having them split into 1E, - and 02
So:
Regex.Split("10E-02*x+sin(x)^2", #"([*()\^\/]|(?<!E)[\+\-])")
Yields:
10E-02
*
x
+
sin
(
x
)
^
2
Building off from BFree's answer, I had the same goal, but I wanted to split on an array of characters similar to the original Split method, and I also have multiple splits per string:
public static IEnumerable<string> SplitAndKeep(this string s, char[] delims)
{
int start = 0, index;
while ((index = s.IndexOfAny(delims, start)) != -1)
{
if(index-start > 0)
yield return s.Substring(start, index - start);
yield return s.Substring(index, 1);
start = index + 1;
}
if (start < s.Length)
{
yield return s.Substring(start);
}
}
Just in case anyone wants this answer aswell...
Instead of string[] parts = Regex.Split(originalString, #"(?<=[.,;])") you could use string[] parts = Regex.Split(originalString, #"(?=yourmatch)") where yourmatch is whatever your separator is.
Supposing the original string was
777- cat
777 - dog
777 - mouse
777 - rat
777 - wolf
Regex.Split(originalString, #"(?=777)") would return
777 - cat
777 - dog
and so on
This version does not use LINQ or Regex and so it's probably relatively efficient. I think it might be easier to use than the Regex because you don't have to worry about escaping special delimiters. It returns an IList<string> which is more efficient than always converting to an array. It's an extension method, which is convenient. You can pass in the delimiters as either an array or as multiple parameters.
/// <summary>
/// Splits the given string into a list of substrings, while outputting the splitting
/// delimiters (each in its own string) as well. It's just like String.Split() except
/// the delimiters are preserved. No empty strings are output.</summary>
/// <param name="s">String to parse. Can be null or empty.</param>
/// <param name="delimiters">The delimiting characters. Can be an empty array.</param>
/// <returns></returns>
public static IList<string> SplitAndKeepDelimiters(this string s, params char[] delimiters)
{
var parts = new List<string>();
if (!string.IsNullOrEmpty(s))
{
int iFirst = 0;
do
{
int iLast = s.IndexOfAny(delimiters, iFirst);
if (iLast >= 0)
{
if (iLast > iFirst)
parts.Add(s.Substring(iFirst, iLast - iFirst)); //part before the delimiter
parts.Add(new string(s[iLast], 1));//the delimiter
iFirst = iLast + 1;
continue;
}
//No delimiters were found, but at least one character remains. Add the rest and stop.
parts.Add(s.Substring(iFirst, s.Length - iFirst));
break;
} while (iFirst < s.Length);
}
return parts;
}
Some unit tests:
text = "[a link|http://www.google.com]";
result = text.SplitAndKeepDelimiters('[', '|', ']');
Assert.IsTrue(result.Count == 5);
Assert.AreEqual(result[0], "[");
Assert.AreEqual(result[1], "a link");
Assert.AreEqual(result[2], "|");
Assert.AreEqual(result[3], "http://www.google.com");
Assert.AreEqual(result[4], "]");
A lot of answers to this! One I knocked up to split by various strings (the original answer caters for just characters i.e. length of 1). This hasn't been fully tested.
public static IEnumerable<string> SplitAndKeep(string s, params string[] delims)
{
var rows = new List<string>() { s };
foreach (string delim in delims)//delimiter counter
{
for (int i = 0; i < rows.Count; i++)//row counter
{
int index = rows[i].IndexOf(delim);
if (index > -1
&& rows[i].Length > index + 1)
{
string leftPart = rows[i].Substring(0, index + delim.Length);
string rightPart = rows[i].Substring(index + delim.Length);
rows[i] = leftPart;
rows.Insert(i + 1, rightPart);
}
}
}
return rows;
}
This seems to work, but its not been tested much.
public static string[] SplitAndKeepSeparators(string value, char[] separators, StringSplitOptions splitOptions)
{
List<string> splitValues = new List<string>();
int itemStart = 0;
for (int pos = 0; pos < value.Length; pos++)
{
for (int sepIndex = 0; sepIndex < separators.Length; sepIndex++)
{
if (separators[sepIndex] == value[pos])
{
// add the section of string before the separator
// (unless its empty and we are discarding empty sections)
if (itemStart != pos || splitOptions == StringSplitOptions.None)
{
splitValues.Add(value.Substring(itemStart, pos - itemStart));
}
itemStart = pos + 1;
// add the separator
splitValues.Add(separators[sepIndex].ToString());
break;
}
}
}
// add anything after the final separator
// (unless its empty and we are discarding empty sections)
if (itemStart != value.Length || splitOptions == StringSplitOptions.None)
{
splitValues.Add(value.Substring(itemStart, value.Length - itemStart));
}
return splitValues.ToArray();
}
Recently I wrote an extension method do to this:
public static class StringExtensions
{
public static IEnumerable<string> SplitAndKeep(this string s, string seperator)
{
string[] obj = s.Split(new string[] { seperator }, StringSplitOptions.None);
for (int i = 0; i < obj.Length; i++)
{
string result = i == obj.Length - 1 ? obj[i] : obj[i] + seperator;
yield return result;
}
}
}
I'd say the easiest way to accomplish this (except for the argument Hans Kesting brought up) is to split the string the regular way, then iterate over the array and add the delimiter to every element but the last.
To avoid adding character to new line try this :
string[] substrings = Regex.Split(input,#"(?<=[-])");
result = originalString.Split(separator);
for(int i = 0; i < result.Length - 1; i++)
result[i] += separator;
(EDIT - this is a bad answer - I misread his question and didn't see that he was splitting by multiple characters.)
(EDIT - a correct LINQ version is awkward, since the separator shouldn't get concatenated onto the final string in the split array.)
Iterate through the string character by character (which is what regex does anyway.
When you find a splitter, then spin off a substring.
pseudo code
int hold, counter;
List<String> afterSplit;
string toSplit
for(hold = 0, counter = 0; counter < toSplit.Length; counter++)
{
if(toSplit[counter] = /*split charaters*/)
{
afterSplit.Add(toSplit.Substring(hold, counter));
hold = counter;
}
}
That's sort of C# but not really. Obviously, choose the appropriate function names.
Also, I think there might be an off-by-1 error in there.
But that will do what you're asking.
veggerby's answer modified to
have no string items in the list
have fixed string as delimiter like "ab" instead of single character
var delimiter = "ab";
var text = "ab33ab9ab"
var parts = Regex.Split(text, $#"({Regex.Escape(delimiter)})")
.Where(p => p != string.Empty)
.ToList();
// parts = "ab", "33", "ab", "9", "ab"
The Regex.Escape() is there just in case your delimiter contains characters which regex interprets as special pattern commands (like *, () and thus have to be escaped.
using System.Collections.Generic;
using System.Text.RegularExpressions;
namespace ConsoleApplication9
{
class Program
{
static void Main(string[] args)
{
string input = #"This;is:a.test";
char sep0 = ';', sep1 = ':', sep2 = '.';
string pattern = string.Format("[{0}{1}{2}]|[^{0}{1}{2}]+", sep0, sep1, sep2);
Regex regex = new Regex(pattern);
MatchCollection matches = regex.Matches(input);
List<string> parts=new List<string>();
foreach (Match match in matches)
{
parts.Add(match.ToString());
}
}
}
}
I wanted to do a multiline string like this but needed to keep the line breaks so I did this
string x =
#"line 1 {0}
line 2 {1}
";
foreach(var line in string.Format(x, "one", "two")
.Split("\n")
.Select(x => x.Contains('\r') ? x + '\n' : x)
.AsEnumerable()
) {
Console.Write(line);
}
yields
line 1 one
line 2 two
I came across same problem but with multiple delimiters. Here's my solution:
public static string[] SplitLeft(this string #this, char[] delimiters, int count)
{
var splits = new List<string>();
int next = -1;
while (splits.Count + 1 < count && (next = #this.IndexOfAny(delimiters, next + 1)) >= 0)
{
splits.Add(#this.Substring(0, next));
#this = new string(#this.Skip(next).ToArray());
}
splits.Add(#this);
return splits.ToArray();
}
Sample with separating CamelCase variable names:
var variableSplit = variableName.SplitLeft(
Enumerable.Range('A', 26).Select(i => (char)i).ToArray());
I wrote this code to split and keep delimiters:
private static string[] SplitKeepDelimiters(string toSplit, char[] delimiters, StringSplitOptions splitOptions = StringSplitOptions.None)
{
var tokens = new List<string>();
int idx = 0;
for (int i = 0; i < toSplit.Length; ++i)
{
if (delimiters.Contains(toSplit[i]))
{
tokens.Add(toSplit.Substring(idx, i - idx)); // token found
tokens.Add(toSplit[i].ToString()); // delimiter
idx = i + 1; // start idx for the next token
}
}
// last token
tokens.Add(toSplit.Substring(idx));
if (splitOptions == StringSplitOptions.RemoveEmptyEntries)
{
tokens = tokens.Where(token => token.Length > 0).ToList();
}
return tokens.ToArray();
}
Usage example:
string toSplit = "AAA,BBB,CCC;DD;,EE,";
char[] delimiters = new char[] {',', ';'};
string[] tokens = SplitKeepDelimiters(toSplit, delimiters, StringSplitOptions.RemoveEmptyEntries);
foreach (var token in tokens)
{
Console.WriteLine(token);
}