Just as replaceFirstIn, replaceAllIn is called on the regular expression that needs to be replaced rather than the string that needs to be modified.
The syntax is identical to replaceFirstIn where ReplaceExpression is the expression you want to replace the previous expression with and SearchString is the string to be modified.
Let’s look at an example where we have a string of letters and numbers, but only want a string of numbers. What we will do is replace all the blocks of letters with the number 1.