c# - StringBuilder: AppendFormat and Capacity -

in code try appendformat message length bigger string builder's capacity:

    static void main(string[] args)     {         stringbuilder sb = new stringbuilder(10);         sb.appendformat("1234567890123"); // 13 characters         console.writeline(sb.capacity);     } 

do know should output (answer @ bottom)?

okay, let's try change code , init stringbuilder capacity, still less string length, example 12:

    static void main(string[] args)     {         stringbuilder sb = new stringbuilder(12);         sb.appendformat("1234567890123"); // 13 characters         console.writeline(sb.capacity);     } 

so, question is: appendformat double start capacity of stringbuilder if string couldn't appened? if appended string's length should 24 characters, capacity become 48?

output code: 20 & 24

does appendformat double start capacity of stringbuilder if string couldn't appended?

yes -- see here.

whenever append operation causes length of stringbuilder object exceed capacity, existing capacity doubled , append operation succeeds.