


In the previous article "PHP String Learning: Dividing Strings into Substrings of Smaller Length", we introduced the method of splitting strings and dividing strings into smaller substrings. This time I will continue to learn and practice PHP strings and see how to extract numeric characters in strings. If necessary, you can refer to it~
The theme of this article is: "Extracting numeric characters from strings". For example, if we give the following string
$str ='0我是123456一段测试的字789符串0';
, how can we remove other characters and only return the substring "01234567890
" composed of the numeric characters in the string? Here are two methods to introduce to you:
First look at the first method:
<?php header("content-type:text/html;charset=utf-8"); function findNum($str) { $str = trim($str); if (empty($str)) { echo ''; }else{ $temp = array('1', '2', '3', '4', '5', '6', '7', '8', '9', '0'); $result = ''; for ($i = 0; $i < strlen($str); $i++) { if (in_array($str[$i], $temp)) { $result .= $str[$i]; } } echo $result; } } $str = '0我是123456一段测试的字789符串0'; findNum($str); ?>
Analyze the above code:
Use
trim($str)
to remove the spaces at both ends, and use the if statement to ensure that the string after removing the spaces is not an empty string.Create a character array containing numbers 0~9 respectively
$temp
Use The for loop traverses the string
$str
, compares each character in$str
with the elements in the$temp
array, and obtains the numeric characters. (Use the in_array function to search whether each character in$str
exists in the$temp
array, so you can determine whether the character is a numeric character).Use "
.=
" to splice the obtained numeric characters together, and then output the spliced string.
Look at the output:
OK, it is the numerical substring "01234567890" that needs to be returned at the beginning of the article!
The following introduces The second method is similar to the first method, except that the in_array() function is replaced by the is_numeric() function.
<?php header("content-type:text/html;charset=utf-8"); function findNum($str) { $str = trim($str); if (empty($str)) { echo ''; }else{ $result = ''; for ($i = 0; $i < strlen($str); $i++) { if (is_numeric($str[$i])) { $result .= $str[$i]; } } echo $result; } } $str = '0我是123456一段测试的字789符串0'; findNum($str); ?>
Analyze the above code:
Use a for loop to traverse the string
$str
, but this time without using the numeric character array and in_array () function to determine whether it is a numeric character, use the is_numeric() function directly. The is_numeric() function can detect whether a variable is a number or a numeric string.Use
is_numeric($str[$i])
in the loop body to determine whether the$str[$i]
character is a number character; if so, take it out and use ".=" to concatenate it into a numeric substring.
Look at the output:
Okay, that’s all. If you want to know anything else, you can click this . → →php video tutorial
Finally, I recommend reading a classic course "PHP String Processing (Jade Girl Heart Sutra Edition)", it's free~ come and learn !
The above is the detailed content of Learn how to remove other characters from PHP strings, leaving only numbers. For more information, please follow other related articles on the PHP Chinese website!

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。


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