## Find prime numbers between the range

 Code Block
`<?php \$start=0;\$end=100;\$prime_numbers=array();for(\$i=\$start;\$i<=\$end;\$i++){	if(is_prime(\$i)==true){		\$prime_numbers[]=\$i;	}} var_dump(\$prime_numbers);function is_prime(\$num){	\$no=\$num;	\$prime=true;	for(\$i=2;\$i<=(\$no/2);\$i++)	{		if(\$no%\$i==0){			\$prime=false;			break;		}	}	return \$prime;} ?>`

## prime no or not

First of all, I want to tell you that what is the prime no.

Prime no is the no which can’t be divided by other than 1 and itself.

## Prime No? Yes : No;

 Code Block
`<?php\$no=8;\$prime=true;for(\$i=2;\$i<(\$no/2);\$i++){    if(\$no%\$i==0){        \$prime=false;        break;    }}if(\$prime==true){    echo "<br/>Number is Prime<br/>";}else{    echo "<br/>Number is not prime<br/>";}?>`

## String is palindrome or not

 Code Block
`<?php\$origing_str = "khan";\$opesite_str="";\$leng = strlen(\$origing_str);\$str_array=str_split(\$origing_str);for(\$i=\$leng-1;\$i>=0;\$i--){    \$opesite_str.= \$str_array[\$i];}if(\$origing_str==\$opesite_str){	echo 'string is palindrome';}else{	echo 'string is not palindrome';}?>`

## Find the opposite in PHP

 Code Block
`<?php\$origing_str = 1234;\$origing_str.="";\$opesite_str="";\$leng = strlen(\$origing_str);\$str_array=str_split(\$origing_str);for(\$i=\$leng-1;\$i>=0;\$i--){	\$opesite_str.= \$str_array[\$i];}echo "Opposite Number: ".(int)\$opesite_str; ?>`

## Array Sorting With Single Loop

There is an unsorted array of integers. write the complete program to find the second largest no in the array without using sorting and max functions. You can only iterate(loop) over the array once.

 Code Block
`<?phpecho "<br/>";\$arr=array(12,52,2,35,95,17,37,42);echo "Before Sorting<br/>";print_r(\$arr);\$tot_arr=count(\$arr);for(\$i=0;\$i<\$tot_arr;\$i++){	if((\$i< (\$tot_arr-1)) && \$arr[\$i]>\$arr[\$i+1]){		\$temp=\$arr[\$i];		\$arr[\$i]=\$arr[\$i+1];		\$arr[\$i+1]=\$temp;		\$i=-1;	}}echo "<br/>After Sorting<br/>";print_r(\$arr);?>`

Output:

Before Sorting
Array ( [0] => 12 [1] => 52 [2] => 2 [3] => 35 [4] => 95 [5] => 17 [6] => 37 [7] => 42 )
After Sorting
Array ( [0] => 2 [1] => 12 [2] => 17 [3] => 35 [4] => 37 [5] => 42 [6] => 52 [7] => 95 )