Python String rfind()用法及代碼示例

用法:

str.rfind(sub[, start[, end]] )

參數：

rfind() 方法最多接受三個參數：

• sub - 這是要在str String 。
• start和結尾(可選)- 在其中搜索子字符串str[start:end]

返回：

rfind() 方法返回一個整數值。

• 如果字符串中存在子字符串，則返回找到子字符串的最高索引。
• 如果字符串中不存在子字符串，則返回 -1。

示例 1：rfind() 沒有開始和結束參數

quote = 'Let it be, let it be, let it be'

result = quote.rfind('let it')
print("Substring 'let it':", result)

result = quote.rfind('small')
print("Substring 'small ':", result)

result = quote.rfind('be,')
if  (result != -1):
  print("Highest index where 'be,' occurs:", result)
else:
  print("Doesn't contain substring")

輸出

Substring 'let it': 22
Substring 'small ': -1
Highest index where 'be,' occurs: 18

示例 2：rfind() 帶有 start 和 end 參數

quote = 'Do small things with great love'

# Substring is searched in 'hings with great love'
print(quote.rfind('things', 10))

# Substring is searched in ' small things with great love' 
print(quote.rfind('t', 2))

# Substring is searched in 'hings with great lov'
print(quote.rfind('o small ', 10, -1))

# Substring is searched in 'll things with'
print(quote.rfind('th', 6, 20))

輸出

-1
25
-1
18