Méthode d'utilisation et exemples de find() pour les chaînes de caractères Python

Python string methods

La méthode find() retourne l'indice de la première apparition de la sous-chaine (si elle est trouvée). Si elle n'est pas trouvée, elle retourne-1.

La syntaxe de la méthode find() est :

str.find(sub[,　start[,　end]])

paramètre find()

The find() method can use up to three parameters:

• sub-　It is the substring to be searched in the str string.

• startandend (Optional)-Search for the substring str[start:end] in it

find() return value

The find() method returns an integer value.

• If the substring is present in the string, it returns the index of the first occurrence of the substring.

• If the substring is not present in the string, it returns-1.

Example1: find() without start and end parameters

quote = 'Let it be, let it be, let it be'
result = quote.find('let it')
print("Substring 'let it':", result)
result = quote.find('small')
print("Substring 'small':", result)
# How to use find()
if (quote.find('be,') !=　-1):
　　print("Contains string 'be,'")
else:
　　print("Not contained string")

When running the program, the output is:

Substring 'let it':　11
Substring 'small':　-1
Contains string 'be,'

Example2: find() with start and end parameters

quote = 'Do small things with great love'
# Search for substring 'hings with great love'
print(quote.find('small things',　10))
# Search for substring ' small things with great love'　
print(quote.find('small things',　2))
# Search for substring 'hings with great lov'
print(quote.find('o small　',　10,　-1))
# Search for substring 'll things with'
print(quote.find('things　',　6,　20))

When running the program, the output is:

-1
3
-1
9

Python string methods