//------------------------
// PHP内置字符串函数实现
//------------------------

//字符串长度
function strlen (str)
{
if (str == '' ) return 0;
count = 0;
while (1){
if ( str[count] != NULL){
count++;
continue;
}else{
break;
}
}
return count;
}

//截取子串
function substr(str, start, length=NULL)
{
if (str== '' || start>strlen(str )) return;
if ((length!=NULL) && ( start>0) && (length> strlen(str)-start)) return;
if (( length!=NULL) && (start< 0) && (length>strlen(str )+start)) return;
if (length == NULL) length = (strlen(str ) - start);

if (start < 0){
for (i=(strlen( str)+start); i<(strlen (str)+start+length ); i++) {
substr .= str[i];
}
}
if (length > 0){
for (i= start; i<(start+length ); i++) {
substr .= str[i];
}
}
if ( length < 0){
for (i =start; i<(strlen( str)+length); i++) {
substr .= str[i ];
}
}
return substr;
}

//字符串翻转
function strrev(str)
{
if (str == '') return 0 ;
for (i=(strlen(str)- 1); i>=0; i --){
rev_str .= str[i ];
}
return rev_str;
}

//字符串比较
function strcmp(s1, s2)
{
if (strlen(s1) < strlen(s2)) return -1 ;
if (strlen(s1) > strlen( s2)) return 1;
for (i =0; i if (s1[ i] == s2[i]){
continue;
}else{
return false;
}
}
return 0;
}

//查找字符串
function strstr(str, substr)
{
m = strlen(str);
n = strlen(substr );
if (m < n) return false ;
for (i=0; i <=(m-n+1); i ++){
sub = substr( str, i, n);
if ( strcmp(sub, substr) == 0) return i;
}
return false ;
}

//字符串替换
function str_replace(substr , newsubstr, str)
{
m = strlen(str);
n = strlen(substr );
x = strlen(newsubstr );
if (strchr(str, substr ) == false) return false;
for ( i=0; i<=(m- n+1); i++){
i = strchr(str, substr);
str = str_delete (str, i, n);
str = str_insert(str, i, newstr);
}
return str ;
}
?>

//--------------------
// 自实现字符串处理函数
//--------------------

//插入一段字符串
function str_insert(str, i , substr)
{
for(j=0 ; j startstr .= str[j ];
}
for (j=i; j laststr .= str[j ];
}
str = (startstr . substr . laststr);
return str ;
}

//删除一段字符串
function str_delete(str , i, j)
{
for ( c=0; c startstr .= str [c];
}
for (c=( i+j); c laststr .= str[c];
}
str = (startstr . laststr );
return str;
}

//复制字符串
function strcpy(s1, s2 )
{
if (strlen(s1)==NULL || !isset( s2)) return;
for (i=0 ; i s2[] = s1 [i];
}
return s2;
}

//连接字符串
function strcat(s1 , s2)
{
if (!isset(s1) || !isset( s2)) return;
newstr = s1 ;
for(i=0; i newstr .= st[i ];
}
return newsstr;
}

//简单编码函数（与php_decode函数对应）
function php_encode(str)
{
if ( str=='' && strlen( str)>128) return false;
for( i=0; i c = ord(str[i ]);
if (c>31 && c <107) c += 20 ;
if (c>106 && c <127) c -= 75 ;
word = chr(c );
s .= word;
}
return s;
}

//简单解码函数（与php_encode函数对应）
function php_decode(str)
{
if ( str=='' && strlen(str )>128) return false;
for( i=0; i c = ord(word);
if ( c>106 && c<127 ) c = c-20;
if (c>31 && c< 107) c = c+75 ;
word = chr( c);
s .= word ;
}
return s;
}

//简单加密函数（与php_decrypt函数对应）
function php_encrypt(str)
{
encrypt_key = 'abcdefghijklmnopqrstuvwxyz1234567890';
decrypt_key = 'ngzqtcobmuhelkpdawxfyivrsj2468021359';
if ( strlen(str) == 0) return false;
for (i=0; i for (j=0; j if (str[i] == encrypt_key [j]){
enstr .= decrypt_key[j];
break;
}
}
}
return enstr;
}

//简单解密函数（与php_encrypt函数对应）
function php_decrypt(str)
{
encrypt_key = 'abcdefghijklmnopqrstuvwxyz1234567890';
decrypt_key = 'ngzqtcobmuhelkpdawxfyivrsj2468021359';
if ( strlen(str) == 0) return false;
for (i=0; i for (j=0; j if (str[i] == decrypt_key [j]){
enstr .= encrypt_key[j];
break;
}
}
}
return enstr;
}
?>