Strings never change. Every += makes a new one.
The problem
This builds 1000 strings to get one.
var line = "";foreach (var item in inventory){ line += item.Name + ", ";}
A string cannot be edited. Each += copies the whole thing into a new one and throws the old away.
The fix
Use a buffer that can grow.
StringBuilder keeps one block of memory and writes into it. You pay for the text once.
- string +=
- a whole new string, every pass
- StringBuilder
- one buffer that grows
- string.Join
- one call, no loop at all
Call ToString once at the end, when you actually need a string.
The fix in code
Append, then ToString once.
using System.Text; var sb = new StringBuilder();foreach (var item in inventory){ sb.Append(item.Name).Append(", ");}var line = sb.ToString();
Same result, one allocation that grows instead of one per item.
The rule
A loop building a string wants a buffer.
- A few pieces
- just use +
- A whole list
- string.Join
- Built in a loop
- StringBuilder
string.Join already does this. Try it before the loop.