regex match any single character (one character only)

Question

How do you match any one character with a regular expression?

I am writing this question and the following answer for a general reference. A number of other questions on Stack Overflow sound like they promise a quick answer, but are actually asking something more specific.

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Answer 1

Match any single character

• Use the dot . character as a wildcard to match any single character.

Example regex: a.c

abc   // match a c   // match azc   // match ac    // no match abbc  // no match 

Match any specific character in a set

• Use square brackets [] to match any characters in a set.
• Use \w to match any single alphanumeric character: 0-9, a-z, A-Z, and _ (underscore).
• Use \d to match any single digit.
• Use \s to match any single whitespace character.

Example 1 regex: a[bcd]c

abc   // match acc   // match adc   // match ac    // no match abbc  // no match 

Example 2 regex: a[0-7]c

a0c   // match a3c   // match a7c   // match a8c   // no match ac    // no match a55c  // no match 

Match any character except ...

Use the hat in square brackets [^] to match any single character except for any of the characters that come after the hat ^.

Example regex: a[^abc]c

aac   // no match abc   // no match acc   // no match a c   // match azc   // match ac    // no match azzc  // no match 

(Don't confuse the ^ here in [^] with its other usage as the start of line character: ^ = line start, $ = line end.)

Match any character optionally

Use the optional character ? after any character to specify zero or one occurrence of that character. Thus, you would use .? to match any single character optionally.

Example regex: a.?c

abc   // match a c   // match azc   // match ac    // match abbc  // no match 

See also

• A quick tutorial to teach you the basics of regex
• A practice sandbox to try things out