StringCount

StringCount["string","sub"]

gives a count of the number of times "sub" appears as a substring of "string".

StringCount["string",patt]

gives the number of substrings in "string" that match the general string expression patt.

StringCount["string",{patt1,patt2,}]

counts the number of occurrences of any of the patti.

StringCount[{s1,s2,},p]

gives the list of results for each of the si.

Details and Options

  • The string expression patt can contain any of the objects specified in the notes for StringExpression.
  • With the default option setting Overlaps->False, overlapping substrings are not treated as separate. With the setting Overlaps->True, StringCount counts substrings that overlap as separate.
  • With Overlaps->All, multiple substrings that match the same string expression are all counted as separate. With Overlaps->True, only the first such matching substring at a given position is counted as separate.
  • Setting the option IgnoreCase->True makes StringCount treat lowercase and uppercase letters as equivalent.
  • StringCount["string",RegularExpression["regex"]] gives the number of substrings matching the specified regular expression.

Examples

open allclose all

Basic Examples  (2)

The number of occurrences of "bb" in the string "abbaabbaa":

Count the number of substrings of the form "axc" for different x characters:

Scope  (5)

Use string patterns:

Regular expressions:

Mixed regular expressions and string patterns:

Count occurrences of either substrings:

StringCount automatically threads over lists of strings:

Options  (2)

IgnoreCase  (1)

The number of occurrences of "a" in "abAB":

Ignore case:

Overlaps  (1)

All substrings in "the cat in the hat" starting and ending with "t":

StringCount does not include overlaps by default:

This includes the overlaps:

This includes overlaps starting at the same position:

Applications  (3)

A 10-million-base random DNA string:

The number of sequences with adenine symmetrically placed:

Find how many words occur in the US Constitution:

The number of occurrences of the word "president":

All strings made of two characters with length 4 and which overlap themselves:

Properties & Relations  (1)

StringCount gives the number of matching substrings:

The length of matching substrings obtained from StringCases:

Introduced in 2004
 (5.1)