函数：strtolower();
if(strtolower($_SESSION[‘rand‘])==strtolower($str_number )){
if
(strtolower($_SESSION[
‘rand‘
])==strtolower($str_number )){
echo "验证码正确";
echo
"验证码正确"
;
}else{
}
else
{
echo "验证码不正确";
"验证码不正确"
验证码不区分大小写
原文：https://www.cnblogs.com/vilucky/p/12327180.html
