StringSubstring - Erlang - e r l a n g : c o o k b o o k

The lists:sublist function is the most general solution. lists:sublist has two forms: (a) the first takes a string and a number of entries to return, and (b) a version that takes a string, a start index (indexed from 1), and an end index. For example:

1> lists:sublist("Hello, World!", 7).
"Hello, "
2> lists:sublist("Hello, World!", 1, 5).
"Hello"
3> lists:sublist("Hello, World!", 8, 12).
"World"

lists:sublist always allocates a new string.

Option 2: String Module

There is also a string module, which contains many more string-specific functions. To take the substring of a string, use the string:substr function. This function has two forms: (a) the first takes a string and a start index (indexed from 1), and (b) a version that takes a string, a start index (indexed from 1), and an end index. For example:

1> string:substr("Hello, World!", 8).
"World!"
2> string:substr("Hello, World!", 1, 5)
"Hello"
3> string:substr("Hello, World!", 8, 12)
"World!"
4> string:substr("Hello, World!", 8, 2).
"Wo"

string:substr always allocates a new string.

As you can see, string:substr and lists:sublist perform largely identical functions.

Discussion

Contributors

Based on work by GordonWeakliem and NoelWelsh.

-- BrentAFulgham - 20 Aug 2004

CookbookForm
TopicType:	Recipe
ParentTopic:	StringRecipes
TopicOrder:	030

e r l a n g : c o o k b o o k

Accessing Substrings

Problem

Solution

Option 1: Generic Lists Module

Option 2: String Module

Discussion

Contributors