Midterm-homework.c

Midterm-homework.c

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

#define BUFFER_SIZE 10000

int isValid(char c)
{
    return ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9');
}

char toUpper(char c) // change into capitalization
{
    if ('a' <= c && c <= 'z')
        return c - 'a' + 'A';
    return c;
}

char decodeCipher(char key, char secret)
{
    key = toUpper(key);
    secret = toUpper(secret);
    if (!('A' <= secret && secret <= 'Z'))
        return secret;
    int offset = key - 'A';
    return (secret - 'A' - offset + 26) % 26 + 'A';
}

char encodeCipher(char key, char character)
{
    key = toUpper(key);
    character = toUpper(character);
    if (!('A' <= character && character <= 'Z'))
        return character;
    int offset = key - 'A';
    return (character - 'A' + offset) % 26 + 'A';
}

char mosLetter[40][10];
char mosCode[40][10];
int totalMos = 0;

void readInput()
{
    FILE *mosTXT = fopen("mos.txt", "r");
    if (mosTXT == NULL) {
        printf("File mos.txt can't be opened\n");
        return;
    }

    while (fscanf(mosTXT, "%s %s", mosLetter[totalMos], mosCode[totalMos]) !=
           EOF) {
        totalMos++;
    }

    fclose(mosTXT);
}

int decodeIndex = 0;
char decode_mos[BUFFER_SIZE] = {'\0'};

void decodeMos()
{
    FILE *decodeTXT = fopen("decode.txt", "r");
    if (decodeTXT == NULL) {
        printf("File decode.txt can't be opened\n");
        return;
    }
    // decode mos input
    char inp[BUFFER_SIZE];
    while (fscanf(decodeTXT, "%s", inp) != EOF) {
        //  printf("Trying to match %s\n", inp);
        int hasMatch = 0;
        for (int i = 0; i < totalMos; i++) {
            if (strcmp(mosCode[i], inp) == 0) {
                decode_mos[decodeIndex++] = mosLetter[i][0];
                hasMatch = 1;
                break;
            }
        }

        if (hasMatch == 0) {
            // printf("No match\n");
            decode_mos[decodeIndex++] = inp[0];
        } else {
            // printf("Matched\n");
        }
    }
    fclose(decodeTXT);
}

int main()
{
    readInput();

    /*printf("================================\n");
    printf("Mos code table\n");
    for (int i = 0; i < totalMos; i++)
        printf("%c %s\n", mosLetter[i][0], mosCode[i]);
    printf("================================\n");
    */

    decodeMos();

    printf("CHOOSE A FUNCTION\n\n(1)Encode\n(2)Decode\n");
    int choose;
    scanf("%d", &choose);
    if (choose == 2) {
        printf("================================\n");
        printf("The data is\n");
        printf("%s\n", decode_mos);
        printf("================================\n");

        // decod cipher
        printf("\nKeyword: ");
        char keyword[BUFFER_SIZE];
        scanf("%s", keyword);
        int len = strlen(decode_mos);
        int lenk = strlen(keyword);
        int idxKeyWord = 0;
        FILE *output_decode = fopen("output_decode.txt", "w");
        for (int i = 0; i < len; i++) {
            char res = decodeCipher(keyword[idxKeyWord], decode_mos[i]);
            if (isValid(res) == 1) {
                idxKeyWord++;
                idxKeyWord = idxKeyWord % lenk;
            }
            printf("%c", res == '|' ? ' ' : res);
            fprintf(output_decode, "%c", res == '|' ? ' ' : res);
        }
        printf("\n");
        return 0;
    } else if (choose == 1) {
        FILE *encodeTXT = fopen("encode.txt", "r");

        char encode[BUFFER_SIZE];
    	fscanf(encodeTXT, "%s", encode);
		printf("String: %s\n", encode);
		printf("Keyword: ");
        char keyword[BUFFER_SIZE];
        scanf("%s", keyword);

        int len = strlen(encode);
        int lenk = strlen(keyword);
        int idxKeyWord = 0;
		FILE* outputEncode = fopen("output_encode.txt", "w");
        for (int i = 0; i < len; i++) {
            char res = encodeCipher(keyword[idxKeyWord], encode[i]);
            if (isValid(res) == 1) {
                idxKeyWord++;
                idxKeyWord %= lenk;
            }
            printf("%c", res == '-' ? '|' : res);
			
			if(isValid(res) == 1) {
				for (int i = 0; i < totalMos; i++) {
					if(mosLetter[i][0] == res) {
            			fprintf(outputEncode, "%s ", mosCode[i]);
						break;
					}
				}

			} else {
            	fprintf(outputEncode, "%c ", res == '-' ? '|' : res);
			}
        }
        printf("\n");
    }
    return 0;
}