How do I make this function take arbitrary strings? - c

Question

So basically, right now, this function can only take 9 words with 10 characters each. How do i make it so that it can take an arbitrary amount of words and characters and sort them accordingly in alphabetical order?
int sortText(){
char name[10][9], tname[10][9], temp[10];
int i, j, n;
printf("Enter the amount of words you want to sort (max 9):");
scanf("%d", &n);
printf("Enter %d words: ",n);
for (i = 0; i < n; i++)
{
scanf("%s", name[i]);
strcpy(tname[i], name[i]);
}
for (i = 0; i < n - 1 ; i++){
for (j = i + 1; j < n; j++){
if (strcmp(name[i], name[j]) > 0){
strcpy(temp, name[i]);
strcpy(name[i], name[j]);
strcpy(name[j], temp);
}
}
}
printf("\n------------------------------------------\n");
printf("%-3s %4s %11s\n", "Input","|", "Output");
printf("------------------------------------------\n");
for (i = 0; i < n; i++)
{
printf("%s\t\t%s\n", tname[i], name[i]);
}
printf("------------------------------------------\n");
}

Answer 1

You have two problems, that each needs to be solved separately, but they can still be solved in a similar way, namely using dynamic memory allocations and more importantly reallocation.
There are two important aspects to remember here, and the first is that a string is an array of characters (with a special terminating character) and that you can have a pointer to an array located anywhere in memory.
If we start with the data-types and how you should store your strings, what you want is an array of arrays, much like you have right now, but allocated dynamically which means you want an array of pointers (to the strings), but since the array of string also needs to be dynamic you need a pointer to an array which contains pointers to other arrays, i.e. a pointer to a pointer to char: char **.
Now when we know what data-type to use, lets think about how to allocate it. To allocate space for a single string in your array, you allocate one char * using the malloc function:
char **strings = malloc(1 * sizeof(char *));
That was the simple part. Now before we start reading the actual string, lets think about how to add a new string to your collection: This is done by reallocating the array of strings you have, using the realloc function:
char **temp_strings = realloc(strings, current_count + 1 * sizeof(char *));
if (temp_string == NULL)
{
// Allocation failed, handle error appropriately
}
strings = temp_strings;
++current_count;
Here the variable current_count is the current length of the array of strings, it should be initially initialized to 1 (as we only have a single string in the array).
Now for the reading of the actual strings, and this is a little more complicated since we actually can't read whole strings (since we don't know how long each line is). Instead we read one character at a time, and end when we hit a newline. We also need to reallocate the string for each character.
Maybe something like this:
int ch;
char *s = NULL;
size_t current_length = 0; // Current length of string
while ((c = fgetc(stdin)) != EOF)
{
if (c == '\n')
break; // Newline, done with the current string
if (s == NULL)
{
s = malloc(2); // Allocate two character: One for c and one for the terminator
}
else
{
// The current length is not including the terminator
// that's why we add two characters
char *temp_s = realloc(s, current_length + 2);
if (temp_s == NULL)
{
// Handle error
}
s = temp_s;
}
s[current_length++] = c;
s[current_length] = '\0'; // Terminate as a string
}
if (s != NULL)
{
// "Add" the string to the array of strings
strings[current_count] = s;
}

Answer 2

For C only you should use char pointer located dynamic.
You can make list by implement a linked list. Then strcmp still work well.
See about linked list here:
http://www.cprogramming.com/tutorial/c/lesson15.html