Can php filter spaces in strings?

php can filter spaces in strings. 3 filtering methods: 1. Use str_replace() to filter all spaces, find all spaces and replace them with empty characters, the syntax is "str_replace(" ","", string)"; 2. Use preg_replace() with regular expressions Use the formula to filter all spaces, the syntax is "preg_replace('/\s /','', string)"; 3. Use trim() to filter the spaces at the beginning and end of the string, the syntax is "trim(string)".

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer

PHP filters string spaces, which is the PHP interview process One of the common basic problems in , it is also the basic knowledge point of PHP that we need to master in daily project development. So how does PHP filter string spaces? Here are several methods to introduce to you.

Method 1. Use the str_replace() function to filter all spaces

We use the built-in function str_replace() to replace substrings in a string or array. The replaced string is passed as a parameter. The correct syntax for using this function is as follows.

str_replace($searchString, $replaceString, $originalString, $count);

The built-in function str_replace() has four parameters. Its detailed parameters are as follows

OptionalIt tells the total number of substitutions made to

Parameter		Description
$searchString	Mandatory	It is the substring or array we want to find and replace
$replaceString	Mandatory	It is the string we want to place in the position of $searchString. The function will check for occurrences of $searchString and replace it with $replaceString. This function will check for an occurrence of $searchString and replace it with $replaceString. It can also be an array.
$originalString	force	It is the original string from which we want to find a substring or a characters to replace.
##$count		$originalString Times

This function returns the final string after all substitutions.

The program below shows how we can remove all spaces from a given string using str_replace() function.

<?php 
header("Content-type:text/html;charset=utf-8");
$searchString = " ";
$replaceString = "";
$originalString = "This is a programming tutorial"; 
 
$outputString = str_replace($searchString, $replaceString, $originalString); 
echo "原字符串：".$originalString."<br>";  
echo "去除空格后的字符串：".$outputString; 
  
?>

We passed a space character as $searchString and an empty string as $replaceString. The output will be a string without spaces.

Now, if we pass in the $count parameter, the function will tell us the number of replacements for this string.

<?php 
header("Content-type:text/html;charset=utf-8");
$searchString = " ";
$replaceString = "";
$originalString = "This is a programming tutorial"; 
 
$outputString = str_replace($searchString, $replaceString, $originalString, $count); 
echo "原字符串：".$originalString."<br>";  
echo "去除空格后的字符串：".$outputString."<br>"; 
echo "替换字数：".$count; 
?>

Method 2. Use preg_replace() function to filter all spaces

You can also use preg_replace() function to delete strings all spaces in . This function can remove not only space characters but also tab characters from a string. The correct syntax for using this function is as follows.

preg_replace($regexPattern, $replacementVar, $original, $limit, $count)

The function preg_replace() accepts five parameters. Its detailed parameters are as follows

ParametersDescription##$regexPattern$replacementVar$original$limit$count

我们将使用模式 /\s+/ 来查找空格。从字符串中删除空格的程序如下。

<?php 
header("Content-type:text/html;charset=utf-8");
$originalString = "This is a programming tutorial"; 

$outputString = preg_replace(&#39;/\s+/&#39;, &#39;&#39;, $originalString); 

echo "原字符串：".$originalString."<br>";  
echo "去除空格后的字符串：".$outputString."<br>"; 
?>

我们知道这个字符串的总替换次数是 4，现在我们将限制替换次数。

<?php 
header("Content-type:text/html;charset=utf-8");
$searchString = " ";
$replaceString = "";
$limit = 2;
$originalString = "This is a programming tutorial"; 
 
$outputString = preg_replace(&#39;/\s+/&#39;, &#39;&#39;, $originalString,$limit); 
echo "原字符串：".$originalString."<br>";  
echo "去除空格后的字符串：".$outputString."<br>"; 

?>

可以看出只替换了两次。

方法3、使用trim()函数过滤字符串开头和结尾的空格

trim() 函数移除字符串两侧的空白字符或其他预定义字符。

trim(string,charlist)

force	It is what we will put in the original string Or the pattern searched in an array
mandatory	It is the string we use to replace the search value or array
force	It is a string or array from which we want to find the value and Replace it.
Optional	This parameter limits the number of replacements
Optional	This parameter tells us the total number of times to replace the original string or array

参数	描述
string	必需。规定要检查的字符串。
charlist	可选。规定从字符串中删除哪些字符。如果省略该参数，则移除下列所有字符： "\0" - NULL "\t" - 制表符 "\n" - 换行 "\x0B" - 垂直制表符 "\r" - 回车 " " - 空格

返回值：返回已修改的字符串。    

示例：过滤字符串开头和结尾的空格

<?php 
header("Content-type:text/html;charset=utf-8");
$str = "  Hello PHP中文网   ";
$newStr = trim($str); 
echo "原字符串:".$str."。<br>";  
echo "去除空格后的字符串:".$newStr."。<br>"; 
?>

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