QBasic Program to Reverse a Number

Write a program in QBasic to reverse a number.

For example,

Input
12345
Output
54321

Steps to Reverse A Number

  1. Let n be the input number.
  2. Declare a variable temp and set temp = n.
  3. Declare a variable num. Set num = 0.
  4. Repeat the following steps while temp > 0
    1. Set r = temp MOD 10. This step stores the rightmost digit of temp in r.
    2. Set num = num * 10 + r. This step adds r at once place of num.
    3. Set temp = temp / 10. This step removes the rightmost digit of temp.
  5. The reverse of N is stored in num.

Reverse a Number in QBasic

CLS
INPUT "Enter a Number: ", n
temp = n
num = 0
WHILE temp > 0
    r = temp MOD 10
    num = num * 10 + r
    ' Note: We are using '\' for division instead of '/'
    ' '\' returns integer number
    ' whereas '/' returns floating number
    temp = temp \ 10
WEND
PRINT "Reverse of"; n; "is: "; num
END

Reverse a Number in QBasic – Using do while

CLS
INPUT "Enter a Number: ", n
temp = n
num = 0
DO
    r = temp MOD 10
    num = num * 10 + r
    ' Note: We are using '\' for division instead of '/'
    ' '\' returns integer number
    ' whereas '/' returns floating number
    temp = temp \ 10
LOOP WHILE temp > 0
PRINT "Reverse of"; n; "is: "; num
END

Reverse a Number in QBasic – Using do until

CLS
INPUT "Enter a Number: ", n
temp = n
num = 0
DO
    r = temp MOD 10
    num = num * 10 + r
    ' Note: We are using '\' for division instead of '/'
    ' '\' returns integer number
    ' whereas '/' returns floating number
    temp = temp \ 10
LOOP UNTIL temp = 0
PRINT "Reverse of"; n; "is: "; num
END

Reverse a Number in QBasic – Using Subroutine

DECLARE SUB reverse

CLS
reverse
END

SUB reverse
    INPUT "Enter a Number: ", n
    temp = n
    num = 0
    WHILE temp > 0
        r = temp MOD 10
        num = num * 10 + r
        ' Note: We are using '\' for division instead of '/'
        ' '\' returns integer number
        ' whereas '/' returns floating number
        temp = temp \ 10
    WEND
    PRINT "Reverse of"; n; "is: "; num
END SUB

Reverse a Number in QBasic – Using Function

DECLARE FUNCTION reverse(n)

CLS
INPUT "Enter a Number: ", n
PRINT "Reverse of"; n; "is: "; reverse(n)
END

FUNCTION reverse (n)
    temp = n
    num = 0
    WHILE temp > 0
        r = temp MOD 10
        num = num * 10 + r
        ' Note: We are using '\' for division instead of '/'
        ' '\' returns integer number
        ' whereas '/' returns floating number
        temp = temp \ 10
    WEND
    reverse = num
END FUNCTION

Output

Read

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