如何将句子中第一个单词的首字母大写? [英] How to capitalize first letter of first word in a sentence?

问题描述

我正在尝试编写一个函数来清理用户输入.

I am trying to write a function to clean up user input.

我并不是想使其完美.我宁愿小写一些名称和首字母缩写，也不愿用大写完整的段落.

I am not trying to make it perfect. I would rather have a few names and acronyms in lowercase than a full paragraph in uppercase.

我认为该函数应使用正则表达式，但我对这些表达式很不好，需要一些帮助.

I think the function should use regular expressions but I'm pretty bad with those and I need some help.

如果以下表达式后跟一个字母，我想将该字母大写.

If the following expressions are followed by a letter, I want to make that letter uppercase.

 "."
 ". " (followed by a space)
 "!"
 "! " (followed by a space)
 "?"
 "? " (followed by a space)

更好的是，该函数可以在."，！"之后添加一个空格.和 "?"如果后面跟着字母.

Even better, the function could add a space after ".", "!" and "?" if those are followed by a letter.

这如何实现?

推荐答案

$output = preg_replace('/([.!?])\s*(\w)/e', "strtoupper('\\1 \\2')", ucfirst(strtolower($input)));

由于修饰符 e 在PHP 5.5.0中已弃用:

Since the modifier e is deprecated in PHP 5.5.0:

$output = preg_replace_callback('/([.!?])\s*(\w)/', function ($matches) {
    return strtoupper($matches[1] . ' ' . $matches[2]);
}, ucfirst(strtolower($input)));

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