REVERSE NUMBER AND STRING

21)C PROGRAM TO REVERSE A NUMBER AND A STRING

(A)REVERSE A NUMBER

LOGIC:- 

• take any number from user which you want to reverse
• using "/" to find the quotient i.e let  num=2351 now divide num/10 = 235.Next using "%" to find the remainder i.e num%10=1 store it.
• again divide the new num which is  235 now we have new num after divide is =23 and remainder is 5. so apply logic that after 1 , 5 is come and so on...
• reverse=reverse*10+remainder  // this code create a reverse.

EXAMPLE:-

(B)REVERSE A STRING:

LOGIC:- we can reverse string from many ways by using string reverse function(strrev()), without strrev() , by using pointers etc.Here 2 ways are given.

EXAMPLE 1 :- BY USING STRREV FUNCTION

 

EXAMPLE 2 :- WITHOUT USING STRREV FUNCTION

• first declare two empty character array(similar to string).
• input string in one array
• now find the length of the input array.
• now using a loop where first character of input array is insert at the last of second array and so on
• now we have a reverse of the string

NOTE:- WE ALSO FIND THE LENGTH OF STRING USING FUNCTION STRLEN().

(C)BY USING RECURSION:

LOGIC:- Recursion means a function call itself.So we create a function which call itself.In this function we write the code to reverse the string

EXAMPLE:- 

TASK:"""TRY WITH POINTER""" WHERE YOU CAN USE SWAPPING TECHNIQUE