珀尔 | rindex()函数

Perl 中的 rindex()函数的操作类似于 index()函数，不同之处在于它返回字符串（或文本）中子字符串（或模式）最后一次出现的位置。如果指定了位置，则返回该位置或之前的最后一次出现。

Syntax:
# Searches pat in text from given Position
rindex text, pattern, Position

# Searches pat in text
rindex text, pattern

Parameters:

• text: String in which substring is to be searched.
• pat: Substring to be searched.
• index: Starting index(set by the user or it takes zero by default).

Returns:
-1 on failure otherwise position of last occurrence.

示例 1：

#!/usr/bin/perl -w
  
$pos = rindex("WelcomeToGeeksforGeeksWorld", "eks");
print "Position of eks: $pos\n";
  
# Use the first position found as the offset 
# to the next search.
  
# Note that the length of the target string is
# subtracted from the offset to save time.
$pos = rindex("WelcomeToGeeksforGeeksWorld", 
                          "eks", $pos - 3 );
print "Position of eks: $pos\n";

输出：

Position of eks: 19
Position of eks: 11

示例 2：

#!/usr/bin/perl -w
  
$pos = rindex("GeeksforGeeks", "eks");
print "Position of eek: $pos\n";
  
# Use the first position found as the 
# offset to the next search.
  
# Note that the length of the target string is
# subtracted from the offset to save time.
$pos = rindex("GeeksForGeeks", "eks", $pos - 2);
print "Position of eek: $pos\n";

输出：

Position of eek: 10
Position of eek: 2