Replacing Morse to English

Hi, working on a college project (only very new to C) and i'm trying to write a code that i input a bunch of morse into the program, but when it runs the morse is translated into english, i know i assume i have to have every morse equal to a letter or number with a space after, two spaces for a word break, then the program will check the sentence and replace each it reads with the correct given translation. I have no idea how to do this properly. The best i've done is a weird concoction that only reads the first character e.g the - or the . Any ideas?
Thanks.
-Teepee

To add, sorry if i didn't use correct tags or post icons, just signed up and first post.

It's hard to give you more ideas, if you don't show your current idea.

Plus, it's hard to show you how without just giving you the code.

This is what i did originally to try, but i don't think that breaks and cases are the right way to go with it, maybe strings or arrays?

Code:

#include <stdio.h> main (){ char enterMorse = '--'; switch(enterMorse) { case '.-': printf("A"); break; case '-...': printf("B"); break; case '-.-.': printf("C"); break; case '-..': printf("D"); break; case '.': printf("E"); break; case '..-.': printf("F"); break; case '--.': printf("G"); break; case '....': printf("H"); break; case '..': printf("I"); break; case '.---': printf("J"); break; case '-.-': printf("K"); break; case '.-..': printf("L"); break; case '--': printf("M"); break; case '-.': printf("N"); break; case '---': printf("O"); break; case '.--.': printf("P"); break; case '--.-': printf("Q"); break; case '.-.': printf("R"); break; case '...': printf("S"); break; case '-': printf("T"); break; case ',,-': printf("U"); break; case '...-': printf("V"); break; case '.--': printf("W"); break; case '-..-': printf("X"); break; case '-.--': printf("Y"); break; case '--..': printf("Z"); break; case '-----': printf("0"); break; case '.----': printf("1"); break; case '..---': printf("2"); break; case '...--': printf("3"); break; case '....-': printf("4"); break; case ',,,,,': printf("5"); break; case '-....': printf ("6"); break; case '--...': printf ("7"); break; case '---..': printf ("8"); break; case '----.': printf ("9"); break; default: printf ("invaliddddddd"); break; } printf ("%c\n", enterMorse); system("pause");

it was just reading the first - in char entermorse

OK, a few things to sort out.

1. 'c' != "c"
In single quotes, you have a character constant, and it can only be a single character.
In double quotes, it's a string, and you can have as many characters as you like.
Whilst you can do switch('c'), you can't do switch("c"), so you have to resort to using strcmp.

2. Split the problem into functions.

Code:

void morse ( const char *morse ) { // Now you can focus on just one letter. } int main ( ) { char morse[] = ".-"; decodeMorse(morse); }

3. Do you know about arrays? Do you know about structures?

I'm not familiar with multi-character literals, but as you discovered they don't work for you in this instance.

Rather, input the morse code as a string which you can then break up into substrings, each corresponding to a single morse code "letter". Then you have a few possible approaches, e.g., computing a unique number from the morse code.

Quote:

Originally Posted by Salem

3. Do you know about arrays? Do you know about structures?

I kind of know arrays, not about structures, currently doing strings and arrays in lectures and classes. Not clicking yet though

You save a lot of copy/paste if you can do this.

Code:

char morseTable[][6] = { ".-", // etc }; char letterTable[][2] = { "A", // etc };

A for loop through one of them will give you an index into the other one - when a match is found.

Would the way you just showed be like this? and is the [6] and [2] how many i can have?

Code:

char morseTable[][26] = {

Code:

".-", "..", "--", // etc }; char letterTable[][26] = { "A","B", "c", "d", // etc };

> Would the way you just showed be like this? and is the [6] and [2] how many i can have?
That's the length of each string.

char morseTable[numberOfMorseSymbols][maxLengthOfMorseCode]

But the compiler will count the left-most dimension for you, based on how many initialisers you provide.

Quote:

only reads the first character

The problem:

'a' is for characters.
"abc" is for string.

Quote:

Double quotes is for string and single quotes for character.

therefore: '--.' is invalid

Quote:

any ideas?

Comparing strings can be difficult...

Code:

#include <stdio.h> #include <string.h> #define morse_A ".-" #define morse_B "-..." #define morse_C "-.-." #define morse_D "-.." #define morse_E "." #define morse_F "..-." #define morse_G "--." #define morse_H "...." #define morse_I ".." #define morse_J ".---" #define morse_K "-.-" #define morse_L ".-.." #define morse_M "--" #define morse_N "-." #define morse_O "---" #define morse_P ".--." #define morse_Q "--.-" #define morse_R ".-." #define morse_S "..." #define morse_T "-" #define morse_U "..-" #define morse_V "...-" #define morse_W ".--" #define morse_X "-..-" #define morse_Y "-.--" #define morse_Z "--.." char morseEntered[10]; int compare(char *string1,char *string2) { int response = 1; for (int i=0;i<=strlen(string1);i++) { if ( string1[i] != string2[i] ) response = 0; }; return response; }; int main(int argc, char *argv[]) { sprintf(morseEntered,".-"); if ( compare(morseEntered,morse_A) ) printf("A"); if ( compare(morseEntered,morse_B) ) printf("B"); if ( compare(morseEntered,morse_C) ) printf("C"); if ( compare(morseEntered,morse_D) ) printf("D"); if ( compare(morseEntered,morse_E) ) printf("E"); if ( compare(morseEntered,morse_F) ) printf("F"); if ( compare(morseEntered,morse_G) ) printf("G"); if ( compare(morseEntered,morse_H) ) printf("H"); if ( compare(morseEntered,morse_I) ) printf("I"); if ( compare(morseEntered,morse_J) ) printf("J"); if ( compare(morseEntered,morse_K) ) printf("K"); if ( compare(morseEntered,morse_L) ) printf("L"); if ( compare(morseEntered,morse_M) ) printf("M"); if ( compare(morseEntered,morse_N) ) printf("N"); if ( compare(morseEntered,morse_O) ) printf("O"); if ( compare(morseEntered,morse_P) ) printf("P"); if ( compare(morseEntered,morse_Q) ) printf("Q"); if ( compare(morseEntered,morse_R) ) printf("R"); if ( compare(morseEntered,morse_S) ) printf("S"); if ( compare(morseEntered,morse_T) ) printf("T"); if ( compare(morseEntered,morse_U) ) printf("U"); if ( compare(morseEntered,morse_V) ) printf("V"); if ( compare(morseEntered,morse_W) ) printf("W"); if ( compare(morseEntered,morse_X) ) printf("X"); if ( compare(morseEntered,morse_Y) ) printf("Y"); if ( compare(morseEntered,morse_Z) ) printf("Z"); return 0; };

Quote:

Originally Posted by Structure

Comparing strings can be difficult...

Code:

#include <stdio.h> #include <string.h> #define morse_A ".-" #define morse_B "-..." #define morse_C "-.-." #define morse_D "-.." #define morse_E "." #define morse_F "..-." #define morse_G "--." #define morse_H "...." #define morse_I ".." #define morse_J ".---" #define morse_K "-.-" #define morse_L ".-.." #define morse_M "--" #define morse_N "-." #define morse_O "---" #define morse_P ".--." #define morse_Q "--.-" #define morse_R ".-." #define morse_S "..." #define morse_T "-" #define morse_U "..-" #define morse_V "...-" #define morse_W ".--" #define morse_X "-..-" #define morse_Y "-.--" #define morse_Z "--.." char morseEntered[10]; int compare(char *string1,char *string2) { int response = 1; for (int i=0;i<=strlen(string1);i++) { if ( string1[i] != string2[i] ) response = 0; }; return response; }; int main(int argc, char *argv[]) { sprintf(morseEntered,".-"); if ( compare(morseEntered,morse_A) ) printf("A"); if ( compare(morseEntered,morse_B) ) printf("B"); if ( compare(morseEntered,morse_C) ) printf("C"); if ( compare(morseEntered,morse_D) ) printf("D"); if ( compare(morseEntered,morse_E) ) printf("E"); if ( compare(morseEntered,morse_F) ) printf("F"); if ( compare(morseEntered,morse_G) ) printf("G"); if ( compare(morseEntered,morse_H) ) printf("H"); if ( compare(morseEntered,morse_I) ) printf("I"); if ( compare(morseEntered,morse_J) ) printf("J"); if ( compare(morseEntered,morse_K) ) printf("K"); if ( compare(morseEntered,morse_L) ) printf("L"); if ( compare(morseEntered,morse_M) ) printf("M"); if ( compare(morseEntered,morse_N) ) printf("N"); if ( compare(morseEntered,morse_O) ) printf("O"); if ( compare(morseEntered,morse_P) ) printf("P"); if ( compare(morseEntered,morse_Q) ) printf("Q"); if ( compare(morseEntered,morse_R) ) printf("R"); if ( compare(morseEntered,morse_S) ) printf("S"); if ( compare(morseEntered,morse_T) ) printf("T"); if ( compare(morseEntered,morse_U) ) printf("U"); if ( compare(morseEntered,morse_V) ) printf("V"); if ( compare(morseEntered,morse_W) ) printf("W"); if ( compare(morseEntered,morse_X) ) printf("X"); if ( compare(morseEntered,morse_Y) ) printf("Y"); if ( compare(morseEntered,morse_Z) ) printf("Z"); return 0; };

Assuming the compiler manages to identify that the strlen call in the loop condition is effectively a loop constant, this code has a similiar time complexity to what Salem suggested in post #8, except that it is inferior because of all that need to repeat the if statements instead of just using a loop.

Note that you should use the standard strcmp (and family) instead of writing your own string comparison function(s) unless you have special reasons to do so.

Quote:

you should use the standard strcmp (and family) instead of writing your own string comparison function(s) unless you have special reasons to do so.

because i like to party.

Quote:

Originally Posted by Structure

Comparing strings can be difficult...

Code:

#include <stdio.h> #include <string.h> #define morse_A ".-" #define morse_B "-..." #define morse_C "-.-." #define morse_D "-.." #define morse_E "." #define morse_F "..-." #define morse_G "--." #define morse_H "...." #define morse_I ".." #define morse_J ".---" #define morse_K "-.-" #define morse_L ".-.." #define morse_M "--" #define morse_N "-." #define morse_O "---" #define morse_P ".--." #define morse_Q "--.-" #define morse_R ".-." #define morse_S "..." #define morse_T "-" #define morse_U "..-" #define morse_V "...-" #define morse_W ".--" #define morse_X "-..-" #define morse_Y "-.--" #define morse_Z "--.." char morseEntered[10]; int compare(char *string1,char *string2) { int response = 1; for (int i=0;i<=strlen(string1);i++) { if ( string1[i] != string2[i] ) response = 0; }; return response; }; int main(int argc, char *argv[]) { sprintf(morseEntered,".-"); if ( compare(morseEntered,morse_A) ) printf("A"); if ( compare(morseEntered,morse_B) ) printf("B"); if ( compare(morseEntered,morse_C) ) printf("C"); if ( compare(morseEntered,morse_D) ) printf("D"); if ( compare(morseEntered,morse_E) ) printf("E"); if ( compare(morseEntered,morse_F) ) printf("F"); if ( compare(morseEntered,morse_G) ) printf("G"); if ( compare(morseEntered,morse_H) ) printf("H"); if ( compare(morseEntered,morse_I) ) printf("I"); if ( compare(morseEntered,morse_J) ) printf("J"); if ( compare(morseEntered,morse_K) ) printf("K"); if ( compare(morseEntered,morse_L) ) printf("L"); if ( compare(morseEntered,morse_M) ) printf("M"); if ( compare(morseEntered,morse_N) ) printf("N"); if ( compare(morseEntered,morse_O) ) printf("O"); if ( compare(morseEntered,morse_P) ) printf("P"); if ( compare(morseEntered,morse_Q) ) printf("Q"); if ( compare(morseEntered,morse_R) ) printf("R"); if ( compare(morseEntered,morse_S) ) printf("S"); if ( compare(morseEntered,morse_T) ) printf("T"); if ( compare(morseEntered,morse_U) ) printf("U"); if ( compare(morseEntered,morse_V) ) printf("V"); if ( compare(morseEntered,morse_W) ) printf("W"); if ( compare(morseEntered,morse_X) ) printf("X"); if ( compare(morseEntered,morse_Y) ) printf("Y"); if ( compare(morseEntered,morse_Z) ) printf("Z"); return 0; };

Your compare function still has undefined behaviour if the length of string1 is longer than string2's length (because would be reading/comparing beyond the end of string2). Try adding a break.

For example:

Code:

int compare(char *string1,char *string2) { int response = 1; for (int i=0;i<=strlen(string1);i++) { if ( string1[i] != string2[i] ) { response = 0; break; } }; return response; };

At least it will work now even though you're relying on the compiler to make the assumption that the strlen() call is invariant for the loop. Assuming it does it's not really the most obvious way to write a function that compares strings.
The is at least one other problem: string1 and string2 not const qualified (i.e. the function prototype should really be int compare(const char *string1, const char *string2)). Another potential problem is the return value which is, for example, different to what the standard function strcmp() would return. If you really want or need the return value to be either 0 or 1 and nothing else why not write !!strcmp(morseEntered,morse_A). I can't see the point of this compare() function

My eyes are bleeding from structure's drain-bamage.

Global variables, a string compare worse than O(N), and an array overrun.

> Comparing strings can be difficult...
No it isn't. It's first chapter stuff in pretty much any C introduction.

Ok, im looking at alot of this and honestly, im thoroughly confused, i think this is beyond the point i'm at right now, im grateful for all of you trying to help though

Quote:

Originally Posted by Temphost

Ok, im looking at alot of this and honestly, im thoroughly confused, i think this is beyond the point i'm at right now, im grateful for all of you trying to help though

Which part do you find confusing?

The idea is to have two parallel arrays of strings such that the element at index i of one array corresponds to the element at index i of the other array, for all valid indices i. So one array stores the letters in Morse code form, the other array stores the letters in English form. Hence, given a letter in Morse code form, you search for it in the first array, thereby finding the index, and then use this index to access the letter in English form in the second array.

Quote:

Originally Posted by laserlight

Which part do you find confusing?

Right now, c in general, i just started it and i don't know all the basics yet, the morse thing i'm asking about was an exam which my class had in may which we all struggled with, which im going over now again to try and use to help me learn c more

Well, it's a pretty silly question for an exam. Here's an attempt written in a way I'd never write it in real life. You really wouldn't write it this way in real life and I find it kind of a dumb question for an exam.

Code:

#include <stdlib.h> #include <stdio.h> #include <string.h> /* Bunch of morse code strings/sequences. */ const char *morse[] = { ".-", //morse code of letter A "-...", //morse code of letter B "-.-." , //morse code of letter C "-.." , //morse code of letter D "." , //morse code of letter E "..-." , //morse code of letter F "--." , //morse code of letter G "...." , //morse code of letter H ".." , //morse code of letter I ".---" , //morse code of letter J "-.-" , //morse code of letter K ".-.." , //morse code of letter L "--" , //morse code of letter M "-." , //morse code of letter N "---" , //morse code of letter O ".--." , //morse code of letter P "--.-" , //morse code of letter Q ".-." , //morse code of letter R "..." , //morse code of letter S "-" , //morse code of letter T "..-" , //morse code of letter U "...-" , //morse code of letter V ".--" , //morse code of letter W "-..-" , //morse code of letter X "-.--" , //morse code of letter Y "--.." //morse code of letter Z }; /* We need this because the letters A through to Z are not guarenteed to be * continguious or ascending by the C standard. We'll use this string (array) * to find, or not, the character/letter that corresponds to the morse string in * the morse[] array. Note that the order of this array (english_chars) must be * the same order as for morse[]; i.e. an index of 1 in bothe morse[] and * english_chars[] corresponds to the index for 'B' */ const char *english_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; /* Given the input string 'morse_str' try and find an index into the 'english_chars' * array that matches the input morse code. If there is no match found, -1 is * returned. If a match is found the index for the english character in * 'english_chars' is returned. * * Basically, search the morse[] array for the string 'str' and return an index * if there was a match and -1 if no match found. If anything other than -1 is * returned then the returned value can be used to look up the english letter in * the "parallel array" called (in this example) 'english_chars' */ int morse_string_to_index(const char *morse_str) { const size_t number_of_letters = sizeof morse / sizeof morse[0]; size_t i; int result; for (i = 0; i < number_of_letters ; i++) { if (strcmp(morse[i], morse_str) == 0) { /* if there is a match */ break; } } /* Test to see if we found a match. If we got to the end of the morse[] * array without any of the strings matching with morse_str then no match * was found and 'i' will be == number_of_letters. If a match was found then * 'i' will be < number_of_letters. If a match was found then return the * index ('i'), otherwise return -1 to indicate nothing found. */ if (i < number_of_letters) result = i; /* Found a match, we want to return that array index */ else result = -1; /* No match, return -1 */ return result; } /* Match up 'index' to the character/letter in the english_chars string (array). * If there is no match then the '\0' (nul) character is returned * * This is "mapping" the index of the first "parallel array" to the value in the * second (the English letter). */ char morse_index_to_char(int index) { const size_t number_of_letters = sizeof morse / sizeof morse[0]; char result; if (index >= 0 && index < number_of_letters) result = english_chars[index]; else result = '\0'; /* to indicate an error, basically */ return result; } /* Given a morse code string (sequence), try and find the corresponding English letter */ char morse_to_english_letter(const char *morse) { int morse_string_index; morse_string_index = morse_string_to_index(morse); return morse_index_to_char(morse_string_index); } void print_morse_to_eng(const char *morse) { char ch; ch = morse_to_english_letter(morse); if (ch == '\0') printf("No morse sequence matched\n"); else printf("Morse sequenece \"%s\" is the letter %c\n", morse, ch); } int main(void) { size_t i; /* Silly test... */ for (i = 0; i < 26; i++) { print_morse_to_eng(morse[i]); } print_morse_to_eng(".-.-.-.-.-.-....."); return 0; }

Edit: It's quite possible that if this was really an exam question that the professor doesn't realise that 'A' to 'Z' are not guaranteed to be contiguous or sequential and probably just wanted, basically, the code in morse_string_to_index()

Quote:

Try adding a break.

Wow, an actual productive idea. I like it.

Quote:

Originally Posted by Structure

Wow, an actual productive idea. I like it.

Yeah, it's a crazy thing to do I know

I can post the actual question given if you guys want it?

Quote:

Originally Posted by Temphost

I can post the actual question given if you guys want it?

Sure, but in the end it's up to you to program a solution if you want to learn.

First, just because you know how to do something doesn't mean you just provide everyone else (who don't know how to do it) with an entire source code. If you ever have the time, which I believe you'll never have, go through the forum guidelines. You don't provide source codes. That's that. Doing so hinders the growth of people who come here to learn as by providing a solution you're basically inhibiting the thought process of the person who needs help. Instead try and help them build up on their logic not provide a darn code which is alien nature to a person new to C++ or any programming language in general. Read the messages sent by Salem, laserlight, john etc on the forum and try and learn how they help others if you really wanna help people here. Not everyone would know whatever you sent in the post as a solution. The guy/girl may not even know what a #define is and it's not his/her fault. If this isn't simple enough to understand then let the others help out. Trying to increase your post counts by posting gibberish isn't going to be of any help to anyone!

Secondly, I don't think you might ever read anything written above cuz you'd probably be partying.

Quote:

Originally Posted by Zeus_

Trying to increase your post counts by posting gibberish isn't going to be of any help to anyone!

Oh, I dunno. Sometimes gibberish is good. E.g. if someone can be bothered understanding the code I wrote below -- i.e. how it works -- then maybe they'll learn something about data structures. Who knows though

Code:

#include <stdio.h> int morse_seq_to_char(const char *mseq) { static const char morsetree[] = " ETIANMSURWDKGOHVF L PJBXCYZQ "; unsigned idx = 0; while (*mseq) { idx = 2 * idx + ((unsigned char)*mseq & 1) + 1; mseq++; } if (idx >= sizeof morsetree) return -1; return morsetree[idx] == ' ' ? -1 : morsetree[idx]; } int main(void) { char buff[255]; while (scanf("%s", buff) == 1) { // Not a great way to read input... someone else can fix int ch = morse_seq_to_char(buff); if (ch != -1) putchar(ch); else puts("\n --- Unknown morse code sequence"); } puts(""); return 0; }

Code:

$ echo ".... --- -.. --- .-." | ./a.out HODOR

I am here to learn it, the question is in the past and even if i got a full working code reply it wouldnt get me anywhere with it, i just know i didnt do it well the first time and wanted to go back to it to try and understand how i should have

Heres the actual question minus the image with the morse and english counterparts, if it helps make it any clearer or i missed details originally.

C101 Home Assignment 2019

Due Date: 2^nd May 2019

Description

You are required to write a program that can convert Morse Code into English text. The program should take a string of ’-’ and ’.’ with a single space in between each full English letter and three spaces between each English word.
For example
‘‘−− −.−− −. .− −− . .. … … . .− −.”
Would decode as the English sentence “MY NAME IS SEAN”. Here is the Morse Code scheme for the alphabet.

Instructions

Insert a string of Morse code directly into the program, i.e. do not use a scanf (as this can be very laborious).
The string can be up to 200 Morse characters long. e.g. the example above is 43 Morse characters long.
Output the corresponding English text.
Note that while you should leave your own test string in the program, I will change it to my own test strings to fully test the program.
If the text is too long you should only use the first 200 Morse characters.
If there is a mistake in the input text you should inform the user where the error is and what it is.

It is up to you to consider what sort of mistakes could be made.
Allocation of Marks

20 marks for adherence to the (deleted college name) C Coding Standard, including commenting headers, naming, indentation.
20 marks for being able to decode individual letters.
20 marks for correctly separating full letters in a line of text.
20 marks for correctly separating full words.
20 marks for reporting errors.

Note: This should be your own work and it should be treated similar to an exam. Your lecturer will clarify any questions you have about what you are being asked, but will not assist you with writing or fixing the code. While you can discuss with your class mates, what you submit must be your own work. Before you start you should draw on paper a flow chart of the system. This will assist you in getting the design of your program correct.

Quote:

Originally Posted by Temphost

You are required to write a program that can convert Morse Code into English text. The program should take a string of ’-’ and ’.’ with a single space in between each full English letter and three spaces between each English word.
For example
‘‘−− −.−− −. .− −− . .. … … . .− −.”
Would decode as the English sentence “MY NAME IS SEAN”. Here is the Morse Code scheme for the alphabet.

My 2nd program doesn't actually do exactly that. Assuming that the input text should be "-- -.-- -. .- -- . .. ... ... . .- -."" and not what's given, my 2nd program decodes it as:

Code:

$ echo "-- -.-- -. .- -- . .. ... ... . .- -." | ./a.out MYNAMEISSEAN

Should be easy enough to adapt (to add the spaces) though

Edit: Although, given the example input it seems kind of difficult to imagine how words can be differentiated (i.e. how does that input signify it should decode as "MY NAME" and not "MYNAME"?) That's probably the hardest part of the assignment, as given, and pretty much impossible if you ask me.

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Maybe you find this more useful:

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I don't think you might ever read anything written

My apologies, i was busy coding awesome stuff in multiple languages including several of my own.

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That's that.

Oh is that so mr. that's thatty ?

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The guy/girl may not even know what a #define is

Please try to follow along.

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i just know i didnt do it well the first time and wanted to go back to it to try and understand how i should have

Tbh if you are really interested in learning, this is something you will be doing very often.

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posting gibberish

:o:o:o

Anyways... problem one is the fact you are using single quotes for strings which is invalid. Double quotes for strings ", single quotes for character '. Technically it should throw an error but i'm guessing the compiler just took the first character.

Code:

case'.-':

I vote to cancel this idiot's account.

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Quote:

Originally Posted by flp1969

Maybe you find this more useful:

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Well, yes. Same difference except I used this tree

Attachment 15838

I started writing an explanation of how my snippet works but I a quick search finds similar implementations (e.g. Morse encoder – PocketMagic) The implementation in that link is similar to the reasoning I went through but still relies, like mine, on implementation defined behaviour (specifically the character set encoding). It's the same general idea though

Edit: Although that article's idea of preorder traversal is different to mine! I would have called my (and their) traversal BFS or level order, not preorder :/