If you call a method that has a reference parameter, you must also write the keyword ref before the argument.

In the following statement, the value of the number variable will be left justified within a field that is 30 spaces wide.string message = String.Format(“{0,-30}”, number);

When you call a string object’s Split method, the method extracts tokens from the string and returns them as integers.

In the following example, there are four tokens:”milk cup cupcake cake cookie”

Methods for modifying strings do not actually modify the calling string object but they return a modified copy of the calling string object.

In C# you can only provide one delimiter per string that you wish to tokenize when calling the Split method.

When using a numeric format specifier such as N, F, or C in an interpolated string, it is possible to specify the number of digits to display after a decimal point.

In the following statement, the value of the number variable will be rounded to four decimal places.string message = String.Format(“The number is: {0,4:N2}”, number);

You can use a subscript expression such as name[3] = ‘A’ to change the value of a character within a string.

A mathematical expression, such as A * B, cannot be passed as an argument to a method containing a reference parameter.