Using String class constructors

There are 8 String class constructors, we can do the following:

1.

String(char* Value)
Initializes a new instance of the String class to the value indicated by a specified pointer to an array of Unicode characters. (***)
~EXAMPLE:




char[] chars = ...{'f','a','n','t','a','s','t','i','c' };


unsafe




...{


    fixed (char* vv = chars)




    ...{


        string name1 = new string(vv);


    }


}

.. name1= “fantastic”
 

 
2.
String(char[] Value)
Initializes a new instance of the String class to the value indicated by an array of Unicode characters.
~EXAMPLE:






char[] chars = ...{'f','a','n','t','a','s','t','i','c' };


String name2 = new String(chars);

.. name2 = “fantastic”
                                                                                                                                                                                                               

 

3.  
String(sbyte* Value)
Initializes a new instance of the String class to the value indicated by a pointer to an array of 8-bit signed integers. (***)
~EXAMPLE:


unsafe




...{


    String name3 = null;




    sbyte[] sbArr = new sbyte[] ...{ 0x41, 0x42, 0x43, 0x00 };


    // Instruct the Garbage Collector not to move the memory


    fixed (sbyte* pAsciiUpper = sbArr)




    ...{


        name3 = new String(pAsciiUpper);


    }


}

.. name3 = “ABC”

                                                                                                                                                                                                               
 
 

4.

String(char c,int count)
Initializes a new instance of the String class to the value indicated by a specified Unicode character repeated a specified number of times.
~EXAMPLE:


string name4 = new String('Y', 20);

.. name4 = “YYYYYYYYYYYYYYYYYYYY”

                                                                                                                                                                                                               
 
 

5. 

String(char* value, int StartIndex, int length)
Initializes a new instance of the String class to the value indicated by a specified pointer to an array of Unicode characters, a starting character position within that array, and a length. (***)
~EXAMPLE:




char[] chars = ...{'f','a','n','t','a','s','t','i','c' };


unsafe




...{


    fixed (char* vv = chars)




    ...{


        string name5 = new string(vv, 2, 5);


    }


}

.. name5 = “ntast”

                                                                                                                                                                                                               
 
 

6.

String(char[] Value, int StartIndex, int length)
Initializes a new instance of the String class to the value indicated by an array of Unicode characters, a starting character position within that array, and a length.
~EXAMPLE:




char[] vv = ...{'f','a','n','t','a','s','t','i','c' };


string name6 = new String(vv, 5, 3);

.. name6 = “sti”;

                                                                                                                                                                                                               
 

7. 

String(sbyte* Value, int StartIndex, int length)
Initializes a new instance of the String class to the value indicated by a specified pointer to an array of 8-bit signed integers, a starting character position within that array, and a length.
~EXAMPLE:


unsafe




...{


    String name7 = null;




    sbyte[] sbArr = ...{ 0x61, 0x62, 0x63, 0x00 };


    // Instruct the Garbage Collector not to move the memory


    fixed (sbyte* pAsciiLower = sbArr)




    ...{


        name7 = new String(pAsciiLower, 0, sbArr2.Length-2);


    }


}

.. name7 = “ab”

                                                                                                                                                                                                               
 
 
8.

String(sbyte* value, int startIndex, int length, System.Text.Encoding enc)
Initializes a new instance of the String class to the value indicated by a specified pointer to an array of 8-bit signed integers, a starting character position within that array, a length, and an Encoding object.
 


unsafe




...{


    string name8 = null;




    sbyte[] asciiChars = new sbyte[] ...{ 0x52, 0x53, 0x54, 0x54, 0x56 };


    UTF8Encoding encoding = new UTF8Encoding(true, true);


 


    // Instruct the Garbage Collector not to move the memory


    fixed (sbyte* pAsciiChars = asciiChars)




    ...{


        name8 = new String(pAsciiChars, 0, asciiChars.Length,encoding);


    }


}

 .. name8 = “RSTTV”
 

 
(***): In C#, this constructor is defined only in the context of unsafe code.
 

*****
To set this compiler option in the VS development environment
1.    Open the project's Properties page.
2.    Click the Build property page.
3.    Select the Allow Unsafe Code check box.