string is immutable and stringbuilder is mutable

Question

can any one explain with examples

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Related Discussion: Most efficient way to concatenate strings?

Answer 1

Immutability Of String[instance is readonly]

    string s="hi";
    //now let s be address 1000
    s+=" there"; 
    //above concatination causes creation of new instance in address location other than 1000
    //with modified value "hi there"

Mutability Of stringbuilder[instance can be modified]

    StringBuilder sbr = new StringBuilder("My Favourite Programming Font is ");
    sbr.Append("Inconsolata")
//append operation only modifies existing instance of sbr rather than creating new instance

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String Vs StringBuilder

• String
1. under System namespace
2. Immutable(readonly) instance
3. performance degrades when continuous change of value occures
4. thread safe
• StringBuilder(mutable string)
1. under System.Text namespace
2. mutable instance
3. shows better perfomance since new changes are made to existing instance

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Related Stackeoverflow Question: Mutability of string when string doesn't change in C#?