morse-decoder-encoder

main.c

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

static const char *alpha[] = {
    ".-",   //A
    "-...", //B
    "-.-.", //C
    "-..",  //D
    ".",    //E
    "..-.", //F
    "--.",  //G
    "....", //H
    "..",   //I
    ".---", //J
    "-.-",  //K
    ".-..", //L
    "--",   //M
    "-.",   //N
    "---",  //O
    ".--.", //P
    "--.-", //Q
    ".-.",  //R
    "...",  //S
    "-",    //T
    "..-",  //U
    "...-", //V
    ".--",  //W
    "-..-", //X
    "-.--", //Y
    "--..", //Z
};
static const char *num[] = {
    "-----", //0
    ".----", //1
    "..---", //2
    "...--", //3
    "....-", //4
    ".....", //5
    "-....", //6
    "--...", //7
    "---..", //8
    "----.", //9
};
static const char **table[] = {alpha, num};

typedef enum kind
{
    ALPHA,
    NUM
} Kind;

typedef struct mtree
{
    char value;
    struct mtree *dot;
    struct mtree *bar;
} MTree;

MTree *root;

void make_tree(void);
void drop_tree(void);
void encode_out(const char *s);
void decode_out(const char *s);

int main(void)
{
    make_tree();
    char *string;
    int choice;

    printf("Enter string : ");
    scanf("%[^\n]%*c", string);

    printf("\n[1] Encode\n[2] Decode\nSelect Operation : ");
    scanf("%d", &choice);

    switch (choice)
    {
    case 1:
        encode_out(string);
        break;
    case 2:
        decode_out(string);
        break;
    default:
        printf("ERROR! Invalid Operation.\n");
    }
    drop_tree();
    return 0;
}

void encode_out(const char *s)
{
    for (;; ++s)
    {
        char ch = *s;
        if (ch == '\0')
            break;
        if (isalpha(ch))
        {
            ch = toupper(ch);
            fputs(table[ALPHA][ch - 'A'], stdout); //`-'A'` depend on the sequence of character code
        }
        else if (isdigit(ch))
            fputs(table[NUM][ch - '0'], stdout);
        else if (ch == ' ')
            fputc('/', stdout); //need rest space skip ?
        else
            ; //invalid character => ignore
        fputc(' ', stdout);
    }
    fputc('\n', stdout);
}
static void decode_out_aux(MTree *tree, const char *s)
{
    if (tree == NULL)
        return;
    if (*s == '\0')
        fputc(tree->value, stdout);
    else if (*s == '/')
        fputc(' ', stdout);
    else if (*s == '.')
        decode_out_aux(tree->dot, ++s);
    else if (*s == '-')
        decode_out_aux(tree->bar, ++s);
}
void decode_out(const char *s)
{
    char *p;
    while (*s)
    {
        p = strchr(s, ' ');
        if (p)
        {
            if (p - s != 0)
            {
                char code[p - s + 1];
                memcpy(code, s, p - s);
                code[p - s] = '\0';
                decode_out_aux(root, code);
            }
            s = p + 1;
        }
        else
        {
            decode_out_aux(root, s);
            break;
        }
    }
    fputc('\n', stdout);
}
static void insert_aux(MTree **tree, char ch, const char *s)
{
    if (*tree == NULL)
        *tree = calloc(1, sizeof(**tree));
    if (*s == '\0')
        (*tree)->value = ch;
    else if (*s == '.')
        insert_aux(&(*tree)->dot, ch, ++s);
    else if (*s == '-')
        insert_aux(&(*tree)->bar, ch, ++s);
}

static inline void insert(char ch, const char *s)
{
    if (*s == '.')
        insert_aux(&root->dot, ch, ++s);
    else if (*s == '-')
        insert_aux(&root->bar, ch, ++s);
}

void make_tree(void)
{
    root = calloc(1, sizeof(*root));
    //root->value = '/';//anything
    int i;
    for (i = 0; i < 26; ++i)
        insert('A' + i, table[ALPHA][i]);
    for (i = 0; i < 10; ++i)
        insert('0' + i, table[NUM][i]);
}
static void drop_tree_aux(MTree *root)
{
    if (root)
    {
        drop_tree_aux(root->dot);
        drop_tree_aux(root->bar);
        free(root);
    }
}
void drop_tree(void)
{
    drop_tree_aux(root);
}