by Given a string ‘s’ and a number ‘n’, write a function that returns a string with each character in s replaced with another character that is ‘n’ positions down the alphabet.
If n is 1, A is replaced with B, B is replaced with C, Z is replaced with A and so on.
If n is 2, A is replaced with C, B is replaced with D, Z is replaced with B and so on.
Algorithm
- Convert the received value n = n % 26.
- Iterate through each character of the string.
- For each character in string.
- Add n to ASCII value of character and save it (say “ch”).
- If character is greater than ‘Z’ then
- Find the value by which character is ahead ‘Z’.
- Final character value should be ‘A’ + (value – 1)
Let’s analyze the full program which solves the above problem.
#include <stdio.h>
#include <string.h>
#include <stdint.h>
void string_encoding (char *input, uint32_t n)
{
if (n == 0)
return;
if (n > 26)
{
n = n % 26;
}
int size = strlen (input);
for (int i = 0; i < size; i++)
{
input[i] = input[i] + n;
if (input[i] > 'Z')
{
input[i] = input[i] - ('Z' + 1) + 'A';
}
}
}
int main ()
{
char input[100];
uint32_t n;
printf ("Enter Input String \n");
scanf ("%s", input);
printf ("Enter position \n");
scanf ("%u", &n);
printf ("Input String: %s \n", input);
string_encoding (input, n);
printf ("Modified String: %s \n", input);
}
Let’s analyze output of the above function.
Enter Input String
ABC
Enter position
1
Input String: ABC
Modified String: BCD
----------------------------------------------------------
Enter Input String
ABC
Enter position
0
Input String: ABC
Modified String: ABC
-----------------------------------------------------------
Enter Input String
ABC
Enter position
25
Input String: ABC
Modified String: ZAB
