Using 2D arrays, my arrays don't appear - c

Question

My programm compiles, and it is ok. When I start it and type "AB", they appear on one line, but when I type "BAAB", the "AB" goes under the "BA". I am stuck here for a long time. I will be very glas if you give a solution for this problem.
//it needs to read input from the keyboard and appear every letter constructed by astersks
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
char line[100] = { 'A', 'B' };
int i;
int row;
int col;
bool A[7][6] = { {0, 0, 1, 0, 0, 0}, //letter A
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 1, 1, 1, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0} };
bool B[7][6] = { {1, 1, 1, 0, 0, 0}, //letter B
{1, 0, 0, 1, 0, 0},
{1, 0, 0, 1, 0, 0},
{1, 1, 1, 1, 0, 0},
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 1, 1, 1, 0, 0} };
int main () {
//reads the input
printf ("Type a word or number, or both: ");
scanf ("%s", line);
// loop for every row of every letter
for (row = 0; row < 7; row++)
{
// loop for every inputed letter
for (i = 0; line[i]; i++)
{
// if letter is A do this...
if (line[i] == 'A')
{
// lopp for every column to read the asterisks
for (col = 0; col < 5; col++) {
if (A[row][col])
printf ("*");
else
printf (" ");
}
printf ("\n");
}
if (line[i] == 'B') {
for (col = 0; col < 5; col++) {
if (B[row][col])
printf ("*");
else
printf (" ");
}
}
}
}
return (0);
}

Answer 1

Trex, what you first need to understand is "What does my code do if I take NO input?". So comment out your initial printf and scanf and check:
//reads the input
// printf ("Type a word or number, or both: ");
// scanf ("%s", line);
Output:
$ ./bin/multi_array_mess
*
*** * *
* * * *
* * *****
**** * *
* ** *
* ** *
****
What values of line produce that output? {'A', 'B'} What happens if line contains anything other than AB? Try just 'A':
$ Type a word or number, or both: A
*
* *
* *
*****
* *
* *
* *
Then with 'B':
$ ./bin/multi_array_mess
Type a word or number, or both: B
*** * * * * **** * ** *****
It should be obvious that a newline is missing somewhere in the loop that prints B. Changing your logic to match the way you print 'A' similar to:
if (line[i] == 'B') {
for (col = 0; col < 5; col++) {
if (B[row][col])
printf ("*");
else
printf (" ");
}
printf ("\n");
}
Provides the desired output if you enter just 'B' in response to your prompt:
$ ./bin/multi_array_mess
Type a word or number, or both: B
***
* *
* *
****
* *
* *
****
What is printed if you enter anything other than 'A' or 'B'? NOTHING. What happens if you enter both 'A' and 'B'? (you get a mess).
So it looks just from tinkering with your program, it was designed to print either A of B using '*' as the character depending on the values of 0 or 1 in your arrays. You can either fix the logic to handle line containing both 'A' and 'B', or you can limit your input to one character at a time.
Since your intent appears to be able to handle multiple characters in line at a time, what happens if we just tweak the loop logic a bit. E.g.:
// loop for every inputed letter
for (i = 0; line[i]; i++)
{
// loop for every row of every letter
for (row = 0; row < 7; row++)
{
// if letter is A do this...
if (line[i] == 'A')
{
Give it a try...
Next, think about how you are prompting for input:
printf ("Type a word or number, or both: ");
Wouldn't it make more sense to limit your request to what your code will provide output for?
printf ("Please enter A or B, or both: ");
After receiving input, wouldn't it more sense to check what your user provided before blindly passing the input to the rest of your program? Something simple will do:
for (i = 0; i < (int)strlen (line); i++)
if (line[i] != 'A' || line[i] != 'B') {
fprintf (stderr, "error: invalid input '%c'.\n", line[i]);
return 1;
}
Now try your program again.
Printing Each Letter on One Row
OK. Now that I know what you are intending, it makes it a bit easier to help. In order to print each array as '*' or ' ' on the same row, you basically have to loop through each row, checking if a given letter is specified in line and print that row for every character you need to print. You can cut down on the code repetition by creating a function to print the row for each array (you can actually use a macro, but we'll leave that for later).
In keeping with the earlier discussion, I added a few sanity checks and created a new character array allowed that holds a list of the current characters you have created arrays for (the allowed characters). Just add to it as you add arrays. You will also note I moved all your global variables inside main. There is nothing wrong with using globals, but use them sparingly, and only when necessary.
Putting the pieces together, you could do something like:
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#define MAXL 100
#define ROWS 7
#define COLS 5
void prn_letter_row (bool a[][COLS+1], size_t row);
int main (void) {
char line[MAXL] = {0};
char allowed[] = "AB";
size_t i, row, len;
i = row = len = 0;
bool A[ROWS][COLS+1] = {{0, 0, 1, 0, 0, 0}, //letter A
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 1, 1, 1, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0}};
bool B[ROWS][COLS+1] = {{1, 1, 1, 0, 0, 0}, //letter B
{1, 0, 0, 1, 0, 0},
{1, 0, 0, 1, 0, 0},
{1, 1, 1, 1, 0, 0},
{1, 0, 0, 0, 1, 0},
{1, 0, 0, 0, 1, 0},
{1, 1, 1, 1, 0, 0}};
/* prompt for input */
while (!*line)
{
printf ("\nType a word or number, or both [A-B only]: ");
if (!fgets (line, MAXL, stdin))
fprintf (stderr, "error: no input provided - 'ctrl+d'.\n");
len = strlen (line); /* get length, remove trailing \n */
if (line[len-1] == '\n')
line[--len] = 0;
char *p = line;
while (*p) { /* check each character against 'allowed' */
if (!strchr (allowed, *p)) {
fprintf (stderr, "error: invalid character '%c'.\n", *p);
*line = 0;
}
p++;
}
}
printf ("valid: %s\n\n", line);
for (row = 0; row < ROWS; row++) {
for (i = 0; i < len; i++) {
switch (line[i]) {
case 'A' : prn_letter_row (A, row);
break;
case 'B' : prn_letter_row (B, row);
break;
}
}
putchar ('\n');
}
return 0;
}
/* print given row for letter */
void prn_letter_row (bool a[][COLS+1], size_t row)
{
size_t i;
putchar (' '); /* provide a space before each letter */
for (i = 0; i < COLS; i++)
if (a[row][i])
putchar ('*');
else
putchar (' ');
}
Use/Output
$ ./bin/chars_from_arrays
Type a word or number, or both [A-B only]: A
valid: A
*
* *
* *
*****
* *
* *
* *
$ ./bin/chars_from_arrays
Type a word or number, or both [A-B only]: B
valid: B
***
* *
* *
****
* *
* *
****
$ ./bin/chars_from_arrays
Type a word or number, or both [A-B only]: AB
valid: AB
* ***
* * * *
* * * *
***** ****
* * * *
* * * *
* * ****

Answer 2

Here is your fixed code
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>
char line[100] = {'A','B'};
int i;
int row;
int col;
// Support only latin aphabet, easly expandable
bool chars[26][7][6] = {
{ {0,0,1,0,0,0 }, //letter A
{1,0,0,0,1,0 },
{1,0,0,0,1,0 },
{1,1,1,1,1,0 },
{1,0,0,0,1,0 },
{1,0,0,0,1,0 },
{1,0,0,0,1,0 }},
{ {1,1,1,0,0,0 }, //letter B
{1,0,0,1,0,0 },
{1,0,0,1,0,0 },
{1,1,1,1,0,0 },
{1,0,0,0,1,0 },
{1,0,0,0,1,0 },
{1,1,1,1,0,0 }},
// to Z
};
int main()
{
printf ("Type a word or number, or both: ");
scanf ("%s",line);
//reads the input
for (row = 0;row<7;row++)
// loop for every row of every letter
{
for (i = 0; line[i]; i++) //loop for every inputed letter
{
for (col = 0;col < 6;col++) // lopp for every column to read the asterisks
{
if (chars[toupper(line[i]) - 'A'][row][col])
{
printf("*");
}
else
printf(" ");
}
}
printf("\n");
}
return (0);
}
You can add multiple character support by forming 3d array like
bool chars[26][7][6] = {
{ {0,0,1,0,0,0 }, //letter A
{1,0,0,0,1,0 },
{1,0,0,0,1,0 },
{1,1,1,1,1,0 },
{1,0,0,0,1,0 },
{1,0,0,0,1,0 },
{1,0,0,0,1,0 }},
{ {1,1,1,0,0,0 }, //letter B
{1,0,0,1,0,0 },
{1,0,0,1,0,0 },
{1,1,1,1,0,0 },
{1,0,0,0,1,0 },
{1,0,0,0,1,0 },
{1,1,1,1,0,0 }},
// to Z
};
Than access to array member
chars[toupper(line[i]) - 'A'][row][col];
in this case you may not use any character if checks only for loops
this will only works with small string sizes, because standard console support up to 80 characters in length, to deal with it you can setup console width, or perform some manipulation with console cursors to break out formed string properly (like SetConsoleCursorPosition) in Windows.
if you want to support all printable chars, your 3d array should start at whitespace char up to 128 character. For more info look to ASCII character table.