Reverse a number in PL/SQL
Prerequisite – PL/SQL introduction
In PL/SQL code groups of commands are arranged within a block. A block group related declarations or statements.
In declare part, we declare variables and between begin and end part, we perform the operations.
Explanation:
Consider the example, input = 12345.
Step 1 : mod(12345,10) = 5
rev:= 0*10 + 5 = 5
num = floor(12345/10) = 1234
Step 2 : mod(1234,10) = 4
rev:= 5*10 + 4 = 54
num = floor(1234/10) = 123
Step 3 : mod(123,10) = 3
rev:= 54*10 + 3 = 543
num = floor(123/10) = 12
Step 4 : mod(12,10) = 2
rev:= 543*10 + 2 = 5432
num = floor(12/10) = 1
Step 5 : mod(1,10) = 1
rev:= 5432*10 + 1 = 54321
num = floor(1/10) = 0
in step 5, num =0 which doesn’t satisfy the while condition and loop terminates.
rev = 54321
More examples:
Input : 123456 Output :654321
Input :87459 Output :95478
Below is the required implementation:
SET SERVEROUTPUT ON ; DECLARE -- declare a number 'num' for reading actual input -- declare another number 'rev' that would be reverse of num num NUMBER; rev NUMBER; BEGIN -- & is used to read input from keyboard num:=# -- initialize rev to 0 rev:=0; -- the loop runs until num is greater than 0 WHILE num>0 LOOP -- mod function is used to find the modulus/ remainder of num when divided by 10 rev:=(rev*10) + mod(num,10); -- floor function is used to obtain a result which is an integer num:=floor(num/10); END LOOP; DBMS_OUTPUT.PUT_LINE( 'Reverse of the number is: ' || rev); END ; / -- Program End |
Output:
Enter value for num : 157439 Reverse of the number is: 934751
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