How to de-allocate an array of characters in c? - c

Question

I'm writing a program that asks the number of strings which i'll then count how many spaces it has.
My problem is when I start a new cycle I can't allocate the array of characters I use to count the spaces.
Thanks in advance.
#include <stdio.h>
#include <string.h>
int main(){
char a[20];
int x, z, esp=0, num;
scanf("%d\n", &num);
int array[num];
for (int i=0;i<num;i++){
scanf("%[^\n]", &a);
z =strlen(a);
for (x=0; x<=z; x++){
if (a[x] == ' '){
esp++;
}
}
array[i] = esp;
esp =0;
}
for (int i=0;i<num;i++){
printf ("%d\n", array[i]);
}
return 0;
}

Answer 1

Problems:
Not having all warnings enabled. Save time, enable them all.
'\n' blocks for more input in scanf("%d\n", &num);
Not checking scanf() return value.
Not limiting input with a width in scanf("%[^\n]", &a);
Wrong type passed in scanf("%[^\n]", &a);
Big one: not consuming the end-of-line with repeated scanf("%[^\n]", &a); calls.
Perhaps more.
Repaired code:
// scanf("%d\n", &num);
if (scanf("%d", &num) != 1) { // '\n' removed
puts("Error1");
return -1;
}
// scanf("%[^\n]", &a);
if (scanf(" %19[^\n]", a) != 1) { // ' ' consumes white-space like \n
puts("Error2");
return -1;
}

Answer 2

On the first scanf, remove \n character, after the first scanf, add getchar() to consume new line character.
Replace second scanf with gets;
Then it will work correctly.
By the way, since gets is unsafe, you can use fgets with stdin parameter and max character count parameter instead of gets.

Answer 3

Thanks to everyone who commented and answered my question, I think I wasn't able to explain myself properly. It's a code which reads a number, the number of the lines of characters which then it'll count the spaces of; my problem started when the code executes a new cycle in which this scanf didn't let me enter the string of characters again: scanf("%[^\n]", &a), but did everything else in the cycle while using the same string.
I'm really new to this, coding and the page itself so thanks for the advices. I was able to find a solution: scanf("%[^\n]%*c, &a)
%*[^\n] scans everything until a \n, but doesn't scan in the \n. The asterisk(*) tells it to discard whatever was scanned.
%*c scans a single character, which will be the \n left over by %*[^\n] in this case. The asterisk instructs scanf to discard the scanned character.
And here is the updated code:
#include <stdio.h>
#include <string.h>
int main(){
char a[20];
int x, z, esp=0, num;
scanf("%d\n", &num);
int array[num];
for (int i=0;i<num;i++){
scanf("%[^\n]%*c", &a);
z =strlen(a);
for (x=0; x<=z; x++){
if (a[x] == ' '){
esp++;
}
}
array[i] = esp;
esp =0;
}
for (int i=0;i<num;i++){
printf ("%d\n", array[i]);
}
return 0;
}