Meaning
Returns the lowest index where a substring occurs in a string, or -1 if absent. Solves the problem of needing a substring's position without exception handling when the target is missing. Reach for it when you need the numeric index of a match rather than just a boolean existence check.
Primary Function
String searching / substring detection
Communicative Purpose
Determine whether a substring exists within a string and at what position.
Pattern
text.find(sub)
Core Structure
... .find(...)
Função primária
String searching / substring detection
Propósito comunicativo
Determine whether a substring exists within a string and at what position.
Situações de gatilho
File processing: checking whether a filename contains a specific extension. Data parsing: locating keyword positions in user input. Validation: finding delimiter positions to split structured text fields.
Contextos
General Python code, data processing scripts, web backends, automation tasks.
Padrão
text.find(sub)
Estrutura central
... .find(...)
Slots de substituição
obj: string expression, sub: substring to search
Colocados típicos
- if condition
- slicing
- startswith
- endswith
Substituições comuns
- 'in' operator (simpler for existence checks but returns no index)
- str.index (raises ValueError instead of returning -1
- forcing explicit error handling)
- re.search (supports regex patterns but adds import and complexity overhead)
Erros comuns
Treating -1 as truthy in a boolean context (cause: -1 is a non-zero integer) → condition always True even when substring absent. Using find() for simple existence checks instead of 'in' (cause: overlooking more readable alternative) → code is less clear and more error-prone. Forgetting find() returns -1 not None (cause: assuming Python returns None for missing values) → downstream None checks silently pass. Confusing find() with index() (cause: similar names and behavior) → unexpected ValueError crashes when substring absent.
Similar / contraste
str.index (raises ValueError if not found), re.search (regex search)
Interferências
Coming from JavaScript: similar behavior (indexOf returns -1); from languages where indexOf raises exception (e.g., some Ruby methods) may expect exception.
Família do chunk
- string searching
- string methods
- substring detection
Nuance
Returns -1 when not found; not ideal for simple existence check; prefer 'in' for readability. Linear time complexity.
Efeito pragmático
Provides fast substring search without raising exceptions.
Dica de memória
Find the needle in the haystack.
Nota
Returns -1 when substring not found; prefer 'in' for simple existence checks.
Upgrade path
Use re.search(pattern, string) for more complex pattern matching
Log in to save chunks.