How do I add multiple strings to an array? - arrays

Question

I want to read all .txt files in the directory and add those file names to an array. Catching the text files part is okay but I am having a problem storing those file names inside an array. What is the mistake I've done here? This is my code.
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <strings.h>
int main()
{
DIR *p;
struct dirent *pp;
p = opendir ("./");
char file_list[10][10];
char shades[10][10];
int i = 0;
if (p != NULL)
{
while ((pp = readdir (p))!=NULL) {
int length = strlen(pp->d_name);
if (strncmp(pp->d_name + length - 4, ".txt", 4) == 0) {
puts (pp->d_name);
strcpy(shades[i], pp->d_name);
}
}
i = i + 1;
(void) closedir (p);
for(int i=0; i<4; i++){
printf("\n %s", &shades[i]);
}
}
return(0);
}

Answer 1

What seems to be a problem here is that 'strings' in C works much different than in C++ or C# or Python.
To make it work you'll need to alloc memory for each string.
If I understood correctly what you want to do, here's an example:
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#define FILE_LIST_MAX 10
int main()
{
DIR *p = opendir("./");
struct dirent *pp;
char **file_list = malloc(FILE_LIST_MAX * sizeof(char*));
int i = 0;
if (p == NULL) {
printf("Could not open current directory" );
return 0;
}
while ((pp = readdir(p)) != NULL) {
int length = strlen(pp->d_name);
printf ("%s\n", pp->d_name);
if(length > 4 && memcmp(pp->d_name + length - 4, ".txt", 4) == 0) {
char filename[length];
sprintf(filename, "%s", pp->d_name);
file_list[i] = malloc(length * sizeof(char));
strcpy(file_list[i], filename);
i++;
}
}
(void) closedir(p);
printf("\n.txt filenames within array");
for(int j = 0; j < i; j++) {
printf("\n%s", file_list[j]);
}
for(int j = 0; j < i; j++) {
free(file_list[j]);
}
free(file_list);
return(0);
}
It's not perfect though as you must manually change file_list capacity in FILE_LIST_MAX
Here's an example output from executing this code:
Much better approach would be implementing a dynamic array of chars which will automatically resizes as necessary.