如何更改字符串中单词的第一次出现 [英] How to change first occurrence of word in a string

问题描述

如何更改字符串中单词的第一次出现?

示例:

$a = "Yo!**Hello** 这是这句话中Hello的第一个词";

到

$b = "Yo! **Welcome** 这是这句话中Hello的第一个词";

解决方案

这有效，虽然有点低效:

$a = "Yo!**Hello** 这是这句话中Hello的第一个词";$a = preg_replace('/Hello/', '欢迎', $a, 1);

另一个流行的答案:

$b = str_replace('你好', '欢迎', $a, 1);

不起作用.str_replace 的第四个参数应该是一个变量，通过引用传递，str_replace 会将其设置为替换次数.>

更好的解决方案是从输入字符串中提取两个子字符串:

1. 第一次出现Hello之前的子串，称之为$s1
2. 第一次出现Hello后的子串，称之为$s2

可以使用strpos来获取位置.

结果是 $s1.'Welcome'.$s2

How do I do to change the first occurrence of a word in a string?

Example:

$a = "Yo! **Hello** this is the first word of Hello in this sentence";

to

$b = "Yo! **Welcome** this is the first word of Hello in this sentence";

解决方案

This works, although a bit inefficient:

$a = "Yo! **Hello** this is the first word of Hello in this sentence";
$a = preg_replace('/Hello/', 'Welcome', $a, 1);

The other popular answer:

$b = str_replace('Hello', 'Welcome', $a, 1);

does not work. The fourth argument of str_replace should be a variable, which is passed by reference and str_replace will set it to the number of replacements made.

A better solution would be to extract two sub-strings from the input string:

1. Sub-string before the first occurrence of Hello, call it $s1
2. Sub-string after the first occurrence of Hello, call it $s2

One can use the strpos to get the position.

Result is $s1.'Welcome'.$s2

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