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# Write a program to display Reverse of any number in PHP ?

• Last Updated : 07 Oct, 2021

Write a program to reverse the digits of an integer.

Examples :

```Input : num = 12345
Output: 54321

Input : num = 876
Output: 678```

It can be achieved using Iterative way or Recursive Way

Iterative Method:

Algorithm:

```Input:  num
(1) Initialize rev_num = 0
(2) Loop while num > 0
(a) Multiply rev_num by 10 and add remainder
of num divide by 10 to rev_num
rev_num = rev_num*10 + num%10;
(b) Divide num by 10
(3) Return rev_num```

Example:

num = 456213
rev_num = 0
rev_num = rev_num *10 + num%10 = 3
num = num/10 = 45621
rev_num = rev_num *10 + num%10 = 20 + 6 = 31
num = num/10 = 4562
rev_num = rev_num *10 + num%10 = 260 + 5 = 312
num = num/10 = 456
rev_num = rev_num *10 + num%10 = 2650 + 4 = 3126
num = num/10 = 45
rev_num = rev_num *10 + num%10 = 2650 + 4 = 31265
num = num/10 = 4
rev_num = rev_num *10 + num%10 = 2650 + 4 = 312654
num = num/10 = 0

Program:

## PHP

 ` 1) {``        ``\$rev_num` `= ``\$rev_num` `* 10 + ``\$num` `% 10;``        ``\$num` `= (int)``\$num` `/ 10;``    ``}``    ``return` `\$rev_num``;``}`` ` `// Driver Code``\$num` `= 456213;``echo` `"Original number is :"``.``\$num``;``echo` `"\r\n"``;``echo` `"Reverse of no. is "``, reversDigits(``\$num``);``?>`

Output

```Original number is :456213
Reverse of no. is 312654```

Time Complexity: O(log(n)), where n is the input number.

Auxiliary Space: O(1)

Recursive Method:

## PHP

 ` 0) {``        ``reversDigits((int)(``\$num` `/ 10));``        ``\$rev_num` `+= (``\$num` `% 10) *``                    ``\$base_pos``;``        ``\$base_pos` `*= 10;``    ``}``    ``return` `\$rev_num``;``}`` ` `// Driver Code``\$num` `= 456213;``echo` `"Original number is :"``.``\$num``;``echo` `"\r\n"``;``echo` `"Reverse of no. is "``,``    ``reversDigits(``\$num``);`` ` `?>`

Output

```Original number is :456213
Reverse of no. is 312654```

Time Complexity: O(log(n)) where n is the input number.

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