I’ve been attempting to make a word soup program in C for an assignment: the program accepts user-inputted words and places them onto an NxN board, where each cell is a character.
However, I’m running into a problem: whenever I try to place a word of length exactly N (the width or height of the matrix), the program fails to fit it properly in a single row or column as intended.
Here’s the full code:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
int input_lower_upper_limit(int inf, int sup, const char *message);
void initial_fill(int N, char board[N][N]);
void input_words(int K, int N, char words[K][N]);
void to_uppercase(char *p, int N);
void insert_into_board(int K, int N, char board[N][N], char words[K][N]);
int main()
{
srand(time(0)); // Will be used later to replace the '.' chars once the words are fitted in
int i, j;
// Initial memory allocation for the board and array of words:
int N = input_lower_upper_limit(10, 35, "Enter the size of the matrix: ");
char (*board)[N] = malloc(N * N * sizeof(char));
if (board == NULL)
{
printf("ERROR: Could not allocate memory for the board.\n");
exit(EXIT_FAILURE);
}
int K = input_lower_upper_limit(N/2, 2*N, "Enter the number of words you want to input: ");
char (*words)[N] = malloc(K * N * sizeof(char));
if (words == NULL)
{
printf("ERROR: Could not allocate memory for the words.\n");
free(board);
exit(EXIT_FAILURE);
}
// Main functionality of the program:
initial_fill(N, board);
input_words(K, N, words);
insert_into_board(K, N, board, words);
for (i = 0; i < N; i++)
{
for (j = 0; j < N; j++)
{
printf("%c ", board[i][j]);
}
printf("\n");
}
// Free all allocated memory:
free(words);
free(board);
return 0;
}
int input_lower_upper_limit(const int inf, const int sup, const char *message) {
int n;
do
{
printf("%s", message);
scanf("%d", &n);
fflush(stdin);
if (n < inf || n > sup) printf("ERROR: The number entered must be between %d and %d.\n", inf, sup);
}
while (n < inf || n > sup);
return n;
}
void initial_fill(const int N, char board[N][N])
{
int i, j;
for (i = 0; i < N; i++)
{
for (j = 0; j < N; j++)
{
board[i][j] = '.';
// board[i][j] = rand()%26 + 65;
printf("%c ", board[i][j]);
}
printf("\n");
}
}
void input_words(const int K, const int N, char words[K][N])
{
int i;
for (i = 0; i < K; i++)
{
printf("Enter word %d: ", i + 1);
fgets(words[i], N+2, stdin);
to_uppercase(words[i], N);
words[i][strcspn(words[i], "\n")] = '\0';
printf("words[%d] = %s\n", i, words[i]);
}
}
void to_uppercase(char *p, const int N)
{
int i;
for (i = 0; i < N; i++)
{
if (p[i] >= 'a' && p[i] <= 'z')
{
p[i] -= 32;
}
}
}
int check_space(int N, int x, int y, int dir, char board[N][N], char *word)
{
int i, len = strlen(word);
for (i = 0; i < len; i++)
{
int nx = x, ny = y;
if (dir == 0) nx += i; // LR
else if (dir == 1) nx -= i; // RL
else if (dir == 2) ny += i; // UD
else if (dir == 3) ny -= i; // DU
if (nx < 0 || nx >= N || ny < 0 || ny >= N || board[nx][ny] != '.')
return 0; // No space or overlap
}
return 1; // Space is free
}
void insert_into_board(const int K, const int N, char board[N][N], char words[K][N])
{
int i, j, h, dir, len;
int x_initial, y_initial;
for (i = 0; i < K; i++) // Iterate over each word
{
len = strlen(words[i]);
int placed = 0;
while (!placed) // Try until placement is successful
{
for (h = 0; h < K; h++)
{
if (strlen(words[h]) > N/2)
{
if (rand()%2) dir = rand()%2;
else dir = rand()%2 + 2;
}
else dir = rand()%4; // 0: LR - 1: RL - 2: UD - 3: DU
}
// Generate valid random starting positions
x_initial = (dir == 0 || dir == 1) ? rand() % (N - len + 1) : rand() % N;
y_initial = (dir == 2 || dir == 3) ? rand() % (N - len + 1) : rand() % N;
printf("Printing before check_space()\n"); // Infinite loop happens here.
if (check_space(N, x_initial, y_initial, dir, board, words[i]))
{
// Place the word if space is valid
for (j = 0; j < len; j++)
{
int x = x_initial, y = y_initial;
if (dir == 0) x += j; // LR
else if (dir == 1) x -= j; // RL
else if (dir == 2) y += j; // UD
else if (dir == 3) y -= j; // DU
board[x][y] = words[i][j];
}
placed = 1; // Placement successful
}
}
}
}
For example, with N = 10, K = 5, inputting a 9-letter word like "cavaliers" will work as intended and results in something like this:
C A V A L I E R S .
. C A V A L I E R S
. . . . . . . . . .
. . . . . . . . . .
C A V A L I E R S .
. . . . . . . . . .
C A V A L I E R S .
. . . . . . . . . .
. . . . . . . . . .
. C A V A L I E R S
However, an infinite loop will happen when the length of the words is exactly equal to N. For example, when a 10-letter word like "tablespoon" is inputted, the error will occur and the program will never stop printing the line "Printing before check_space()", which is where I think my code is failing.
(One) expected result:
T A B L E S P O O N
N O O P S E L B A T
. . . . . . . . . .
. . . . . . . . . .
T A B L E S P O O N
N O O P S E L B A T
. . . . . . . . . .
T A B L E S P O O N
. . . . . . . . . .
. . . . . . . . . .
Actual result: Program enters an infinite loop.
I’ve tried adjusting the starting position calculation numbers and verifying space availability with checks, but I’m still missing something. Any insight into how I can fix the program to properly fit the max size is appreciated.
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