How to resolve the algorithm Morse code step by step in the C programming language

Published on 7 June 2024 03:52 AM
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How to resolve the algorithm Morse code step by step in the C programming language

Table of Contents

Problem Statement

Morse code is one of the simplest and most versatile methods of telecommunication in existence. It has been in use for more than 175 years — longer than any other electronic encoding system.

Send a string as audible Morse code to an audio device   (e.g., the PC speaker).

As the standard Morse code does not contain all possible characters, you may either ignore unknown characters in the file, or indicate them somehow   (e.g. with a different pitch).

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Morse code step by step in the C programming language

This C program converts text to Morse code beeps using the beep command. It defines Morse code representations for each character and uses helper functions to generate the appropriate beep commands. Here's how it works:

  • Constants and Definitions:

    • ascii: An array of characters representing the English alphabet, numbers, and punctuation.
    • itu[]: An array of Morse code representations (as strings) for each character in ascii.
    • dd[2]: An array of pointers to character arrays dih and dah, which will store the beep commands for dit and dah, respectively.
    • medium: A string to represent the duration of a medium space between dits and dahs.
    • word: A string to represent the duration of a space between words.

  • append Function:

    • Adds the appropriate beep commands for a given Morse code representation to the input string s. It iterates through the Morse code string, appending dih for dots and dah for dashes, followed by a medium space.

  • translate Function:

    • Takes an input string i and converts it to Morse code beep commands, storing the result in the output string o.
    • For each character in the input string, it finds the corresponding Morse code representation in itu by searching for the uppercase version of the character in ascii.
    • If no Morse code representation is found, it appends a 'word' space to separate words.
    • Otherwise, it appends the Morse code representation and a medium space.
    • Finally, it adds a word space at the end of the output string.

  • main Function:

    • Parses command-line arguments to set the duration of a dit (default: 100 milliseconds).
    • Calculates the durations of dah, medium space, and word space based on the dit duration.
    • Reads lines of text from standard input.
    • For each line, it calls the translate function to convert it to Morse code beep commands and prints the result.

Source code in the c programming language

/*

  David Lambert, 2010-Dec-09

  filter producing morse beep commands.

  build:
    make morse

  use:
    $ echo tie a. | ./morse
    beep -n -f 440 -l 300 -D 100 -n -D 200 -n -f 440 -l 100 -D 100 -n -f 440 -l 100 -D 100 -n -D 200 -n -f 440 -l 100 -D 100 -n -D 200 -n -D 400 -n -f 440 -l 100 -D 100 -n -f 440 -l 300 -D 100 -n -D 200 -n -f 440 -l 100 -D 100 -n -f 440 -l 300 -D 100 -n -f 440 -l 100 -D 100 -n -f 440 -l 300 -D 100 -n -f 440 -l 100 -D 100 -n -f 440 -l 300 -D 100 -n -D 200 -n -D 400 -n -D 400

  bugs:
    What is the space between letter and punctuation?
    Demo truncates input lines at 71 characters or so.

 */

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

#define BIND(A,L,H) ((L)<(A)?(A)<(H)?(A):(H):(L))
/*
  BIND(-1,0,9) is 0
  BIND( 7,0,9) is 7
  BIND(77,0,9) is 9
*/

char
  /* beep args for */
  /* dit  dah     extra space */
  dih[50],dah[50],medium[30],word[30],
  *dd[2] = {dih,dah};
const char
  *ascii = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.,?'!/()&:;=+-_\"$@",
  *itu[] = {
     "13","3111","3131","311","1","1131","331","1111","11","1333","313","1311","33","31","333","1331","3313","131","111","3","113","1113","133","3113","3133","3311","33333","13333","11333","11133","11113","11111","31111","33111","33311","33331","131313","331133","113311","133331","313133","31131","31331","313313","13111","333111","313131","31113","13131","311113","113313","131131","1113113","133131"
  };

void append(char*s,const char*morse) {
  for (; *morse; ++morse)
    strcat(s,dd['3'==*morse]);
  strcat(s,medium);
}

char*translate(const char*i,char*o) {
  const char*pc;
  sprintf(o,"beep");
  for (; *i; ++i)
    if (NULL == (pc = strchr(ascii,toupper(*i))))
      strcat(o,word);
    else
      append(o,itu[pc-ascii]);
  strcat(o,word);
  return o;
}

int main(int ac,char*av[]) {
  char
    sin[73],sout[100000];
  int
    dit = 100;
  if (1 < ac) {
    if (strlen(av[1]) != strspn(av[1],"0123456789"))
      return 0*fprintf(stderr,"use: %s [duration]   dit in ms, default %d\n",*av,dit);
    dit = BIND(atoi(av[1]),1,1000);
  }
  sprintf(dah," -n -f 440 -l %d -D %d",3*dit,dit);
  sprintf(dih," -n -f 440 -l %d -D %d",dit,dit);
  sprintf(medium," -n -D %d",(3-1)*dit);
  sprintf(word," -n -D %d",(7-(3-1)-1)*dit);
  while (NULL != fgets(sin,72,stdin))
    puts(translate(sin,sout));
  return 0;
}

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