Is this two patterns of String Concatenation consume same amount of memory?
//Method 1
String testString = "Test " + " string " + " content";
//Method 2
String testString = "Test ";
testString = testString + " string ";
testString = testString + " content";
Should we avoid both of these methods and use StringBuilder class ?
Method 2 would result in more allocation of memory, string object shall be created to store the following combinations
1) "Test "
2) " String"
3) "Test string"
4) " Content"
5) "Test String Content"
Where in case of Method 1 just one string shall be created
1) "Test string Content"
Method 1 is should be preferred among these two methods
StringBuilder class is more efficient when you need to build a string that involves combining many string values.
Yes, StringBuilder is the better option. In all the other cases you describe you are creating multiple new strings since strings are immutable in C# and can't be changed. This causes c# to simulate changes to strings by creating new strings.
Method one could be converted to a single string. There is no need to concatenate fixed substrings to build the string
In my opinion,it is a big difference between these two method. After building,in method 1,string testString = "Test string content", but in method 2,string testString = "Test ", in run-time,they are also different,in method 1,string testString just refrence to an address in immutable,but in method 2,the clr allocate the new memory in heap and combine the strings together. And i think StringBuilder is a good way for combining string frequently.
.Format()orStringBuilderaccording to context. The dana's links have very good examples. And as there has mentioned,you will see me never using+operator on strings.