【获得英文字符串的首字母】

substr($str, 0, 1);

mb_substr($str, 0, 1, 'utf-8');

参考：https://stackoverflow.com/questions/1972100/getting-the-first-character-of-a-string-with-str0
参考：https://thisinterestsme.com/php-get-first-character-string/

【获得中文拼音字符串的首字母】

<?php
function getFirstCharacter($str)
{
    if (empty($str)) {return '';}
    $fchar = ord($str{0});
    if ($fchar >= ord('A') && $fchar <= ord('z')) {
        return strtoupper($str{0});
    }

    $s1 = iconv('UTF-8', 'gb2312', $str);
    $s2 = iconv('gb2312', 'UTF-8', $s1);
    $s = $s2 == $str ? $s1 : $str;
    $asc = ord($s{0}) * 256 + ord($s{1}) - 65536;

    switch ($asc) {
        case ($asc < -20319):
            return null;
            break;
        case ($asc <= -20284):
            return 'A';
            break;
        case ($asc <= -19776):
            return 'B';
            break;
        case ($asc <= -19219):
            return 'C';
            break;
        case ($asc <= -18711):
            return 'D';
            break;
        case ($asc <= -18527):
            return 'E';
            break;
        case ($asc <= -18240):
            return 'F';
            break;
        case ($asc <= -17923):
            return 'G';
            break;
        case ($asc <= -17418):
            return 'H';
            break;
        case ($asc <= -16475):
            return 'J';
            break;
        case ($asc <= -16213):
            return 'K';
            break;
        case ($asc <= -15641):
            return 'L';
            break;
        case ($asc <= -15166):
            return 'M';
            break;
        case ($asc <= -14923):
            return 'N';
            break;
        case ($asc <= -14915):
            return 'O';
            break;
        case ($asc <= -14631):
            return 'P';
            break;
        case ($asc <= -14150):
            return 'Q';
            break;
        case ($asc <= -14091):
            return 'R';
            break;
        case ($asc <= -13319):
            return 'S';
            break;
        case ($asc <= -12839):
            return 'T';
            break;
        case ($asc <= -12557):
            return 'W';
            break;
        case ($asc <= -11848):
            return 'X';
            break;
        case ($asc <= -11056):
            return 'Y';
            break;
        case ($asc <= -10247):
            return 'Z';
            break;
    }

}
echo getFirstCharacter('?#哈哈哈！');

参考：https://blog.csdn.net/zhezhebie/article/details/77235243
参考：https://www.cnblogs.com/YFYQ/p/13220526.html

【获取英文姓名的首字母】

这段代码可以根据用户输入的英文姓名，分析出姓名的首字母输出，比如”Billy Bob” to “B.B.”

<?php
function initials($name){
$nword = explode(" ",$name);
foreach($nword as $letter){
$new_name .= $letter{0}.'.';
}
return strtoupper($new_name);
}
echo initials('John Doe');
?>