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Reversing a number of unknown digits

Reversing a number of unknown digits - C Programming example

This C program code will take a number as an input and will return its reversed form as the output.


C Programming example
Reversing a number

C Programming Code

#include<stdio.h>
#include<conio.h>
main()
{
    int n,reve;
    printf("Input the number you want to reverse \n");
    scanf("%d",&n);
    reve=0;
    while(n!=0)
    {
        reve=reve*10;
        reve=reve+n%10;
        n=n/10;
    }
    printf("The desired reversed number is %d",reve);
    getch();
}

Output of the C program


C programming example
Reversing a number output

Explanation of  the C program

·         #include<stdio.h>
#include<stdio.h>
Ø  This are called header file.A header file is a file with extension .h which contains C function declarations and macro definitions to be shared between several source filesThe C programming language provides many standard library functions for file input and output. These functions make up the bulk of the C standard library header <stdio.h>.In the other hand  <conio.h> is a C header file used mostly by MS-DOS compilers to provide console input/output. It is not part of the C standard library or ISO C. This header declares several useful library functions for performing "console input and output" from a program.
·         main()
Ø  In C, program execution starts from the main() function. The main function can in-turn call other functions. When main calls a function, it passes the execution control to that function. The function returns control to main when a return statement is executed or when end of function is reached.
·         Int age,year;
Ø  int is a variable or data type. A variable declared to be of type int can be used for storing integers.. Here we declare “n” and “reve” variable in int type.
·         printf() function
Ø  C uses printf() function to write from the input devices. This function has been declared in the header file called stdio.h . Any text written within the pair of quotes ("") is displayed as such by printf() function on the screen. 
·         scanf() function
Ø  This function is used to get input from the user of the program. scanf(“%d,&age) is used here. So, this program will read in a integer value for “age” variable that the user enters on the keyboard (%d is for integer values. As there is “&n”, the number user enters will be the value of “n” variable).
reve=0;
Here we have declared before the loop that the value of reve is 0.
    while(n!=0)
    {
        reve=reve*10;
        reve=reve+n%10;
        n=n/10;
    }
    printf("The desired reversed number is %d",reve);
While loop is used in this program to make this simple, easily executable and understandable.
The condition for the loop is n!=0 . In C programming != means not equals to. So basically the condition stands as long as n doesn’t become equal to 0.
Then the loop is started with { and then we have set that
 reve = reve *10;
Reve = reve + n%10;
N= n/10
So lets take a number such as 1234.
So here reve was previously set as 0. So for the first turn
Reve = 0*10
Reve = 0+1234%10;
So here reve is = 1234%10 = 4 as the reminder is $ and as this is integer value the program won’t read any decimal point numbers.
Reve=4
And after that in the loop n is now = 123
N=123/10
And the loop goes on.
Then Reve = 4*10=40
Reve= 40+ 123%10=40+3=43
Then n=12
And in the same way the loop goes on.
Until n reaches the value of ) or less than one in this case as decimal point numbers isn’t accepted in integer so decimal point will also be considered as 0.
Then finally the loop is ended with}
printf("The desired reversed number is %d",reve);
    getch();

And printf is written to show the output and finally getch(); is written to end the program.

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