Caesar cipher for numbers in C

Question

I want to make a Caesar cipher for numbers. (Add 3 to all digits)

Input: 52 Output:85

Input:954 Output:287

Input: -10457 Output:-43780

I'll be very glad if someone helps me with this.

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I tried this but when I input the number less than 5 digits it outputs 3 to beginning

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When I input 52 it outputs 33385

#include<stdio.h>
#include<stdlib.h>

int main() {

int number,operation;

printf("Enter the number: ");
scanf("%d",&number);

printf("%d", ((number/10000)+3)%10);
printf("%d", (((number % 10000)/1000)+3)%10);
printf("%d", (((number % 1000)/100)+3)%10);
printf("%d", (((number % 100)/10)+3)%10);
printf("%d\n", ((number % 10)+3)%10);

printf("press 1 to continue or 2 for exit.");
scanf("%d",&operation);

switch(operation) {
    case 1:
            printf("Enter the number: ");
scanf("%d",&number);

printf("%d", ((number/10000)+3)%10);
printf("%d", (((number % 10000)/1000)+3)%10);
printf("%d", (((number % 1000)/100)+3)%10);
printf("%d", (((number % 100)/10)+3)%10);
printf("%d\n", ((number % 10)+3)%10);


        break;


    case 2:


        break;
}


return 0;

}

Answer 1

Here is the general algorithm:

• write the number in ASCII into a buffer,
• iterate over the characters in the buffer,
• for each character,
  • if it's a digit, add 3,
  • if the resulting ASCII code is bigger than '9', subtract 10

Writing this algorithm in C is an exercise you should perform yourself as part of your educational process. Skipping this exercise, will prevent you to become smarter.

Answer 2

You have first to iterate over every digit of your number.
Then, for each digit, add 3 to the number and use a modulo 10 ( % 10 ) to retrieve only the last digit of your number.
You'll have then to concatenate each digit together to build you caesar-ciphered string.