使用动态 memory 分配将文件中的字符串存储在二维数组中

Question

At the end of this question you will find a piece of code that I am trying to write to read a file called words.txt with the following strings:

uno dos tres cuatro cinco seis siete ocho nueve diez

The aim of the code is to be able to store the strings in a two-dimensional array with dynamic memory allocation. This means it would need to work with any file that has strings.

I would need to check:

• Why the code is not working.
• How can I make it so that it stores whatever number of words the file has.

Thank you very much guys!

#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
#include <string.h>

int main()
{

char c, *mystring[20];
int i = 0;
FILE *fich;

setlocale(LC_CTYPE,"spanish");
identifica();
    
fich = fopen("words.txt", "r");

do
{
    mystring[i] = malloc (20 * sizeof(char));
    fscanf("%s", mystring[i]);
    printf ("%s", mystring[i]);
}
while ((c=fgetc(fich))!=EOF);

return 0;
}

Answer 1

• You forgot to pass fich to fscanf() . (This is why your code won't work)
• Checking if fscanf() is successful should be performed.
• You can use realloc() for dynamic re-allocation.
• You should increment i for storeing all strings.
• Maximum length of string to read should be specified to avoid buffer overrun.

Try this:

#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
#include <string.h>

int main()
{

    char **mystring = NULL;
    int i = 0;
    FILE *fich;

    setlocale(LC_CTYPE,"spanish");
    identifica();
        
    fich = fopen("words.txt", "r");

    for (;;)
    {
        char* next = malloc (20 * sizeof(char));
        if (fscanf(fich, "%19s", next) == 1)
        {
            printf ("%s", next);
            mystring = realloc(mystring, sizeof(*mystring) * (i + 1));
            mystring[i] = next;
            i++;
        }
        else
        {
            free(next);
            break;
        }
    }

    return 0;
}