#include <stdio.h>
#include <string.h>
#define STR_LEN 50
#define ASCII_LETTER_A 97
#define LETTERS 26
void decrypt(char* cipher, int n);
int main(void)
{
    int key = 0;
    char string[STR_LEN] = { 0 };

    printf("Enter cipher to decrypt: ");
    fgets(string, STR_LEN, stdin);
    string[strcspn(string, "\n")] = 0; //added a command that changes the fget's new line symbol into a char 0 ('0') Yup. That's something that we didn't learn! Thank you stackoverflow!

    printf("Enter decryption key: ");
    scanf("%d", &key);
    getchar();

    decrypt(string, key);

    printf("Decrypted text: ");
    puts(string);

    getchar();
    return 0;
}
void decrypt(char* cipher, int n)
{
    int i = 0, j = 0, lenStr = 0;
    char newStr[STR_LEN] = { 0 };
    lenStr = strlen(cipher);
    for (i = lenStr - 1, j = 0; i >= 0; j++, i--)
    {
        *(newStr + j) = *(cipher + i);
    }

    for (i = 0; i < strlen(newStr); i++)
    {
        *(cipher + i) = (*(newStr + i) + n - ASCII_LETTER_A) % LETTERS + ASCII_LETTER_A;
        //puts(cipher);
    }
}