String – LearnC#WithDarko

Substring

A substring is any sequence of characters that is contained in a string. We use Substring method when we want to create a new string that is based on original string. Replace method is used when we want to change parts of original string and create new one. IndexOf is used when we want to locate first occurrence of certain substring in string.

string originalString = "Today we will learn Substring method";

//Index of is zero based so first character will be "T".
int newIntCreatedWithIndexOf = originalString.IndexOf("o");

//Substring is zero based so sixth character will be "6", and this method will
//create new string starting of character "w" including next 7 characters.
string newStringCreatedWithSubstring = originalString.Substring(6, 6);

//Replace method will replaces all occurrences of a specified substring with a new value(new string)
//so try adding expanding originalString to see results.
string newStringCreatedWithReplace = originalString.Replace("we", "you");

Console.WriteLine(newIntCreatedWithIndexOf);
Console.WriteLine(newStringCreatedWithSubstring);
Console.WriteLine(newStringCreatedWithReplace);

string originalString = "Today we will learn Substring method";

//Index of is zero based so first character will be "T".

int newIntCreatedWithIndexOf = originalString.IndexOf("o");

//Substring is zero based so sixth character will be "6", and this method will

//create new string starting of character "w" including next 7 characters.

string newStringCreatedWithSubstring = originalString.Substring(6, 6);

//Replace method will replaces all occurrences of a specified substring with a new value(new string)

//so try adding expanding originalString to see results.

string newStringCreatedWithReplace = originalString.Replace("we", "you");

Console.WriteLine(newIntCreatedWithIndexOf);

Console.WriteLine(newStringCreatedWithSubstring);

Console.WriteLine(newStringCreatedWithReplace);

How to create new string using Multiple existing strings?

That process is called concatenation and all it basically does is append one string at the end of another string. In next example we will create 3 string and concatenate them. For this example Gangsta Lorem Ipsum is used.

string firstString =
"Lorizzle ipsum dolizzle sit sheezy, doggy adipiscing elizzle. Yo tellivizzle velit, dope volutpizzle, suscipit quis, stuff vel, brizzle. ";

string secondString =
"Pellentesque fo shizzle my nizzle crocodizzle. Funky fresh erizzle. Shiz izzle dolizzle dapibus sizzle boom shackalack fizzle. Maurizzle yo mamma nibh shiz turpis. Mammasay mammasa mamma oo sa izzle tortizzle. Pellentesque eleifend rhoncizzle nisi.";
string thirdString =
"In hizzle habitasse bow wow wow dictumst. Mammasay mammasa mamma oo sa dapibizzle. Curabitur tellizzle urna, pretizzle ass, mattis ac, eleifend vitae, nunc. Gizzle suscipizzle. Integer sempizzle funky fresh sizzle purus.";

string finalString = firstString + secondString + " " + thirdString;
Console.WriteLine(finalString);

string firstString =

"Lorizzle ipsum dolizzle sit sheezy, doggy adipiscing elizzle. Yo tellivizzle velit, dope volutpizzle, suscipit quis, stuff vel, brizzle. ";

string secondString =

"Pellentesque fo shizzle my nizzle crocodizzle. Funky fresh erizzle. Shiz izzle dolizzle dapibus sizzle boom shackalack fizzle. Maurizzle yo mamma nibh shiz turpis. Mammasay mammasa mamma oo sa izzle tortizzle. Pellentesque eleifend rhoncizzle nisi.";

string thirdString =

"In hizzle habitasse bow wow wow dictumst. Mammasay mammasa mamma oo sa dapibizzle. Curabitur tellizzle urna, pretizzle ass, mattis ac, eleifend vitae, nunc. Gizzle suscipizzle. Integer sempizzle funky fresh sizzle purus.";

string finalString = firstString + secondString + " " + thirdString;

Console.WriteLine(finalString);

As you can see new string is created using simple addition. Notice on third operation ” “, we have created a new string with only one blank space. Why? Because when we create new string we have to add it ourselves. Look at the end of first string, you can see that there is empty space at the end, so we did not have to add between firstString and secondString .

That’s all for now regarding string in future we will talk some more about them.

Tomorrow we will talk about reference types so be sure co check in again!

Strings are one of the most useful types in .Net, and since you’ll be using it almost every day, let’s see what we can learn about String.

MSDN: A string is a sequential collection of Unicode characters that is used to represent text.

Strings are a reference type but in some ways it behaves like a value type. For instance, String is immutable, meaning you cannot change content of a string.

Strings can be null.

You can compare two strings.

Maximum size of a string is 2Gb.

Common Operations with Strings

Strings are hard-coded with literals. There are two types of literals: “regular literal” and “verbatim literal”.

//regular literal
string firstString = "It's a beautiful day";

//verbatim literal
string secondString = @"It's a beautiful day";

Console.WriteLine(firstString);
Console.WriteLine(secondString);

//regular literal

string firstString = "It's a beautiful day";

//verbatim literal

string secondString = @"It's a beautiful day";

Console.WriteLine(firstString);

Console.WriteLine(secondString);

If you try running a program, the output will be the same. So how do we know which type of literal to use? When you have a simple text that can be written in one line and does not contain escape characters, you will typically use regular expressions. Verbatim literals are for example useful when you write SQL code.

Let’s try out some common operations with strings using the following well-known sentence: The quick brown fox jumps over the lazy dog.

//regular literal
            string firstString = "The \"quick\" \n brown fox\n \'jumps\' over \\the\\ lazy dog";

            //verbatim literal
            string secondString = @"The ""quick""
brown fox
'jumps' over \the\ lazy dog";

            Console.WriteLine(firstString);
            Console.WriteLine(secondString);

//regular literal

string firstString = "The \"quick\" \n brown fox\n \'jumps\' over \\the\\ lazy dog";

//verbatim literal

string secondString = @"The ""quick""

brown fox

'jumps' over \the\ lazy dog";

Console.WriteLine(firstString);

Console.WriteLine(secondString);

\n – newline

\” – double quotes

\’ – single quote

\\ – backslash

Trim text

A very common operation, and all it does is basically remove empty space at the beginning, end or both. Remember, because strings are immutable, String itself will not be changed.

string output = "    test immutability   ";

Console.WriteLine(output.Trim());      //Trims both beginning and end
Console.WriteLine(output.TrimStart()); //Trims beginning
Console.WriteLine(output.TrimEnd());   //Trims end
Console.WriteLine(output);             //displays string as it is

string output = " test immutability ";

Console.WriteLine(output.Trim()); //Trims both beginning and end

Console.WriteLine(output.TrimStart()); //Trims beginning

Console.WriteLine(output.TrimEnd()); //Trims end

Console.WriteLine(output); //displays string as it is

How to Check if String Is Empty

string output = "    test if empty   ";

if (output.Length != 0)
{
	Console.WriteLine("Output is not empty");
}

if (output != String.Empty)
{
	Console.WriteLine("Output is not empty");
}

if (!String.IsNullOrEmpty(output))
{
	Console.WriteLine("Output is not empty");
}

string output = " test if empty ";

if (output.Length != 0)

{

Console.WriteLine("Output is not empty");

}

if (output != String.Empty)

{

Console.WriteLine("Output is not empty");

}

if (!String.IsNullOrEmpty(output))

{

Console.WriteLine("Output is not empty");

}

All the scenarios above bring about the same result. But there are a few things to be aware of. Length method is the fastest one, both Length and Empty methods create the same code in IL, but in my opinion, the last approach is the easiest one to read and it also checks the strings for null.

Thank you for following me so far and be sure to check in tomorrow because in the next post we will continue covering Strings.

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CategoryString

String Part 2

Substring

How to create new string using Multiple existing strings?

String Part 1

Common Operations with Strings

Trim text

How to Check if String Is Empty