PHP字符串比较函数strcmp()和strcasecmp()使用总结

in strcmp(string str1,string str2)?????????????? //区分字符串中字母大小写地比较
int strcasecmp(string str1,string str2)??????????????? //忽略字符串中字母大小写地比较

<?php
$username = "Admin";
$password = "lampBrother";
?
//不区分大小写的比较,如果两个字符串相等返回0
if(strcasecmp($userName,"admin")== 0){
echo "用户名存在";
}
//将两个比较的字符串相应的函数转成全大写或全小写后,也可以实现不区分大小写的比较
if(strcasecmp(strtolower($userName),strtolower("admin")) == 0){
echo "用户名存在";
}
?
//区分字符串中字母的大小写比较
switch(strcmp($password,"lampbrother")){
case 0:
echo "两个字符串相等<br>"; break;
case 1:
echo "第一个字符串大于第二个字符串<br>"; break;
case -1:
echo "第一个字符串小于第二个字符串<br>"; break;
}
?>

<?php
//定义一个包括数字值的数组
$files = array("file11.txt","file22.txt","file1.txt","file2.txt");
?
function mySort($arr,$select = false){
????for($i=0;$i<count($arr);$i++){
????????for($j;$j<count($arr)-1;$j++){
????????//如果第二个参数为ture则使用strcmp()函数比较大小
????????????if($select){
????????????//前后两个值比较结果大于0则交换位置
????????????????if(strcmp($arr[$j],$arr[j+1])>0){
????????????????????$tmp = $arr[$j];
????????????????????$arr[$j] = $arr[$j+1];
????????????????????$arr[$j+1] = $tmp;
????????????????}
???????????//如果第二个参数为false则使用strnatcmp()函数比较大小
???????????}else{
????????????//如果比较结果大于0交换位置
????????????????if(strnatcmp($arr[$j],$arr[$j+1])>0){
????????????????????$tmp = $arr[$j];
????????????????????$arr[$j] = $arr[$j+1];
????????????????????$arr[$j+1]; = $tmp;
????????????????}
????????????}
????????}
????}
return $arr; //排序后的数组
}
print_r(mySort($files,true));???????? //选择按字典顺序排序： file1.txt file11.txt file2.txt file22.txt
print_r(mySort($files,false));????????? //选择按自然顺序排序：file1.txt file2.txt file11.txt file22.txt
?>