Regular Expressions and In-Place Slice Manipulation in Go

Regular expressions are very useful for parsing strings. If you need to replace a substring or split up an array, you should consider using regular expressions. I will admit that I am not an expert in regards to using them, however, I will not dismiss their usefulness. You may find the RexEgg.com Regex Cheat Sheet very useful.

In Go, the regexp package includes many useful functions that utilize regular expressions.

Here is a simple CLI program that calculates the sum of the integer values in a string. It splits the string into a slice and then sums up all of the integer values in the slice. In this application, the string is split up using the regular expression [^0-9]+. The ^ indicates that that we do not want to match on a character that is an integer within the range of [0-9]. While the + “greedy” quantifier indicates that we want to match when there are one or more characters. In this example, we are simply delimiting the string based on non-digit values such as letters and other special characters.

One important thing to note about func (*Regexp) Split is that it creates an empty element in the slice if it starts splitting the string at the first or last element. In this example, this is handled by catching the error that is thrown when strconv.Atoi(intSlice[i]) fails to convert a string to an integer value at a given index. After an error is thrown, the bad index which is delete in place by taking the valid indexes up to the bad index and then appending the indexes that follow it. This is implemented with intSlice = append(intSlice[:i], intSlice[i:]...). After you remove the element, the length of the slice needs to be decremented.

SEE: SliceTricks

USAGE:
go run .\stringSum.go st1ngW1thIn7s

Screenshot:

Golang String Sum Windows
Golang String Sum Windows

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