#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <string.h>

#define MAX_PHRASE_LENGTH 100

void EncodePhrase(char *original, char *encoded);
char EncodeCharacter(char c);

int main(void)
{
    char phrase[MAX_PHRASE_LENGTH];
    char encoded[MAX_PHRASE_LENGTH];

    printf("Enter phrase to encode: ");
    gets(phrase);

    EncodePhrase(phrase, encoded);

    printf("Encoded: %s\n", encoded);

    return 0;
}


void EncodePhrase(char *original, char *encoded)
{
//declaring variable
int i = 0;

    // using a while loop to encode one character at a time
    while ( original[i] != NULL) {

        // sending one character to be encoded
        encoded[i] = EncodeCharacter(original[i]);

        // incrementing i
        i++;

    }

    // adding null to the end of encoded
    encoded[i] = EncodeCharacter(original[i]);

}

char EncodeCharacter(char c)
{

    // using an if statement to either add or minus 13 to get the correctly encode the character
    if ((c>64) && (c<78)) {

        c = c + 13;
    }

    else if ((c>77) && (c<91)) {

        c = c - 13;
    }

    else if((c>96) && (c<110)) {

        c = c + 13;
    }

    else if((c>109) && (c<123)) {

        c = c - 13;
    }

return c;
}