help on caesar cipher program?

To encrypt a character:

char plain = [get plain input from someplace]

plain = Character.toLowerCase(plain);

char cipher = (plain - 'a' + shift)%26 + 'a';

[store or output the char in cipher somewhere]

Decryption uses the same calculation, but adds 26-shift instead of shift:

plain = (cipher - 'a' + 26 - shift)%26 + 'a';

here it is in C

you can translate to Java

#include <stdio.h>

#include <ctype.h>

void crypt(char *,char *,int);

int main(void){

// caesar cypher programme

char i[]="testingxxx";

char o[100],o2[100];

int j=0;

int off=3;

crypt(i,o,off);

printf("%s\n",o);

crypt(o,o2,-off);

printf("%s\n",o2);

return 0;

}

void crypt(char * i ,char * o ,int off){

while(*i ){

*o++ ='A'+( (toupper(*i++)-'A'+26+off)%26);

}

*o=0;

return;

}