replace() 函数是 PHP 中的一个函数，主要处理字符串，旨在通过搜索需要替换的字符串来替换任何字符串。搜索字符串的模式可以是需要替换整个搜索字符串的方式，也可以是可以被给定字符串或数组中搜索到的替换字符串替换的数组。 Replace() 函数是 PHP 中的内置函数，它返回带有替换值的新字符串或数组。该函数强制接受四个参数或实参，即 search_val、replace_val、subject_val 和 count。
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PHP 替换语法
下面给出的是语法：
str_replace(search_val, replace_val, subject_val, count)
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语法流程的参数表示方式如下：
-
search_val： search_val 参数表示字符串和数组类型。该参数指定需要搜索的字符串，并用搜索到的字符串替换
-
replace_val:replace_val参数代表字符串和数组类型。该参数指定需要替换参数search_val搜索到的字符串。
-
subject_val: subject_val参数代表字符串和数组类型，需要用replace_val替换并用search_val搜索。
-
count： count 是一个可选值，当该值被设置并替换为使用 subject_val 对字符串执行替换操作的总数时传递。
替换函数在 PHP 中如何工作？
PHP 中的replace() 函数是一个内置函数，用于替换给定字符串中需要替换的所有可能参数，因此它有一些需要遵循的工作标准：
- Some mandatory function in PHP involves these parameters like search_val, replace_val, subject_val and count without which the working remains incomplete.
- Some very important criteria to be kept in mind, like if search_val with string and replace_val with string gets searched in the subject_val string then gets substituted by replace_val arguments string of the corresponding string and its arguments.
- If number of arguments in the element of replace_val comes out to be lesser than needed in search_val then it will be replacing the value or element with the empty string.
- The other case which arise and says for replacement also can include array or string with some values.
- Let’s consider the array or string with elements then the entire string will get searched within the subject_val.
- Count value also plays a very important role simultaneous to search_val and replace_val in a way that this argument tries to get passed from the function and its value will set to total number of operations performed for replacement of strings and that string should be string with subject_val.
- The return value for replace function() comes out to be a string i.e. a general string or the string can be string with all the occurrences of replaced value.
- This function is considered as case sensitive function but when compared to str_ireplace() function the str_ireplace() function performs a case-insensitive search.
- This function is considered binary safe as well.
- This function supports in a full fledge mode in versions 4+.
- The optional value of count has another significance which means count function is added in PHP version more than 5.0.
- Earlier Versions of PHP less than 4 involves function which involves quite a lot of complex functions such as find and replace which was indeed making the entire function of string find and replace very cumbersome. It will cause empty find indexes and interplay of internal pointers of arrays.
- All these complexities of find and replace got overcome with the count function being introduced in the PHP with versions 4+ .
- Search functionality and replace function needs lot of attention and focus as both will be used internally in order to perform the functionality with respect to the search operation.
- Sometimes there is a misconception between str_replace() method and str_ireplace() method but the difference is not much very minute difference lies with the fact that both seals with the case sensitive and case insensitive modes respectively.
- Overall string_replace() function works with four mandate parameters which provides re-usability and flexibility to programmers at the time of implementation.
Examples of PHP replace
Given below are the examples mentioned :
Example #1
This program demonstrates the replace() function in PHP which first finds for the string and then replaces the value of the string with some part as defined. It makes the entire php string replaced with some value as shown in the output.
Code:
<!DOCTYPE html>
<html>
<body>
<p>Let's Find for the string "Life_in_writing" and replace the value of writing with "Anusua"</p>
<?php
echo str_replace("writing","Anusua","Life_in_writing!");
?>
</body>
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Output
Example #2
This program demonstrates an array of fruit which is trying to replace the particular value of the fruit like guava string with apple as shown in the output.
Code:
<!DOCTYPE html>
<html>
<body>
<p>Find the array with fruit guava and then substitute it with another fruit Apple.</p>
<?php
$ar_ray = array("guava","kiwi","apple","orange");
print_r(str_replace("guava","apple",$ar_ray,$k));
echo "<br>" . "replaced_fruit: $k";
?>
</body>
</html>登录后复制
Output:
Example #3
This program demonstrates the substitution of string with elements and values of String with some subject_val string as the string value is less it will get substituted easily as show shown in the output.
Code:
<!DOCTYPE html>
<html>
<body>
<?php
$search = array("Welcome","Everyone!");
$replace_str = array("Zee");
$arr_ay = array("Welcome","All",":)");
print_r(str_replace($search,$replace_str,$arr_ay));
?>
</body>
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Output:
Example 4
This program demonstrates the ireplace_string() which acts as case insensitive when compared with the replace() function as shown in the output.
Code:
<!DOCTYPE html>
<html>
<body>
<p>find the string "All is good" and then make it replaced with the capital letter EVERYONE!</p>
<?php
echo str_ireplace("EVERYONE!","Anusua","All is good");
?>
</body>
</html>登录后复制
Output:
Conclusion
PHP replace() is a function which gives programmers flexibility and scope of re-usability at the time of execution and lets user to use function for searching and replacing string accordingly. It gives users a view of implementation in terms of requirement when it comes to adopting the functionality. Overall a function which plays a significant role in PHP.
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