Perl | String 函数(长度、lc、uc、index、rindex)
原文:https://www . geesforgeks . org/perl-string-functions-length-LC-UC-index-rindex/
Perl 中的字符串是包含在某些类型的引号中的字符序列。Perl 字符串可以包含 UNICODE、ASCII 和转义序列字符。Perl 像任何其他编程语言一样，提供各种函数来操作字符串。Perl 的一些字符串函数如下:
- 长度()
- lc()
- uc()
- 索引()
- rindex()
length(): 这个函数用于查找字符串中的字符数。这个函数返回字符串的长度。下面是说明这种方法的程序。
-
Example 1:
```perl
Perl program to demonstrate
string length function
string
my $s = "geeksforgeeks";
using length function &
displaying length
print(length($s),"\n"); ```
输出:
```perl 13
```
-
Example 2:
```perl
Perl program to demonstrate
string length function
string
my \(s = "#\)%HeLLo CSHARP &+#*";
using length function &
displaying length
print(length($s),"\n"); ```
输出:
```perl 19
```
lc(): 这个函数返回字符串的小写版本。下面是说明这种方法的程序。
-
Example 1:
```perl
Perl program to demonstrate
string lc function
string
my $s = "GEEKSFORGEEKS\n";
using lc function &
displaying result
print("To lower case: "); print(lc($s),"\n"); ```
输出:
```perl To lower case: geeksforgeeks
```
-
Example 2:
```perl
Perl program to demonstrate
string lc function
string
my $s = "GEEKS\n";
using lc function &
displaying result
print("To lower case: "); print(lc($s),"\n"); ```
输出:
```perl To lower case: geeks
```
uc(): 这个函数返回字符串的大写版本。下面是说明这种方法的程序。
-
Example 1:
```perl
Perl program to demonstrate
string uc function
string
my $s = "geeksforgeeks";
using uc function &
displaying result
print("To Upper Case: "); print(uc($s),"\n"); ```
输出:
```perl To Upper Case: GEEKSFORGEEKS
```
-
Example 2:
```perl
Perl program to demonstrate
string uc function
string
my $s = "GeekS\n";
using uc function &
displaying result
print("To Upper Case: "); print(uc($s),"\n"); ```
输出:
```perl To Upper Case: GEEKS
```
index(): 此方法将从字符串中的指定位置搜索子字符串，并返回子字符串在字符串中第一次出现的位置。如果位置被省略，它将从字符串的开头开始搜索。此方法将采用两个参数，即原始字符串和必须搜索的子字符串。
示例:
# Perl Program to illustrate
# the index() function
# !/usr/bin/perl
use warnings;
use strict;
# string
my $st = "GeeksforGeeks\n";
# substring
my $subs = "for";
# using index function
my $r = index($st, $subs);
# displaying result
print(qq\The substring $subs found at position $r in string $st\);
输出:
The substring for found at position 5 in string GeeksforGeeks
rindex() 该函数与 index()相同，只是它返回字符串中最后一次出现的文本。此外，可以给出第三个参数，该参数返回该位置之前或该位置处的位置。它从字符串的末尾开始搜索，而不是从开头开始搜索。下面是说明这种方法的程序。
例 1:
# Perl Program to illustrate
# the rindex() function
# !/usr/bin/perl
use warnings;
use strict;
# string
my $st = "GeeksforGeeks\n";
# substring
my $subs = "for";
# using rindex function
my $r = rindex($st, $subs);
# displaying result
print(qq\The substring $subs found at position $r in string $st\);
输出:
The substring for found at position 5 in string GeeksforGeeks
例 2:
# Perl Program to illustrate
# the rindex() function with
# three parameters
# !/usr/bin/perl
# using rindex() function
$p = rindex("GeeksForGFGGeeksgeeksforGFG", "GFG");
print "Founded position of GFG $p\n";
# Use the first position found
# as the offset to the next search.
# The length of the target string
# is subtracted from the offset
# to save time.
$p = rindex("GeeksForGFGGeeksgeeksforGFG", "GFG", $p-7);
print "Founded position of GFG $p\n";
输出:
Founded position of GFG 24
Founded position of GFG 8
