PHP has a forward query (find an element in an array)

function  seq_sch($array, $n,  $k){
    
      
   $array[$n] =  $k;  
   for($i=0;  $i<$n; $i++){
    
      
       if( $array[$i]==$k){
    
      
           break;  
       }  
   }  
   if ($i<$n){
    
      
       return  $i;  
   }else{
    
      
       return -1;  
   }  
}  

Time complexity
If a violent algorithm is used to search in an ordered array, that is, one by one traversal comparison, then the time complexity is O(n); however, after using binary search, because half of the search interval can be discarded each time, so Will reduce the time complexity to O(logn).