如何验证第一个字符必须以AZ开头

Question

在PHP中,如何验证用户输入,如下例所示.

示例有效输入

$input ='abkc32453';
$input ='a32453';
$input ='dsjgjg';

示例无效输入

$input ='2sdf23';
$input ='2121adsasadf';
$input ='23142134';

Answer 1

if(ctype_alpha($input[0])){
//first character is alphabet
}
else {
//first character is invalid
}