How do they search inside a string

What is the most efficient way to do this? There must be some better me开发者_如何学Cthod other than brute force.

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Depends on length of string, size of alphabet and whether repeated searching: Knuth-Morris-Pratt, Rabin-Karp, etc.

See String searching algorithm

Knuth-Morris-Pratt algorithm

Rabin-Karp algorithm