Program containing fscanf fails to compile - c

Question

As someone who is pretty new to C, I'm still trying to wrap my head around the massive amount of functions.
One in particular is giving me a lot of problems.
I'm trying to use fscanf but I keep getting a strange error:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char **argv)
{
FILE *dict = fopen(argv[1], "r");
// skim through every word in a dictionary
while (fscanf(dict, "%s", word) != EOF)
{
// iterate through every chracter in the word
for (int i = 0, int j = strlen(word); i < j; i++)
{
printf("%c", word[i]);
}
printf("\n");
}
return 1;
}
I'm trying to create a loop that skims through every single word in a file that is just a series of words.
I'm assuming that the code I've written does just that, storing each word in a string called "word".
Unfortunately, I keep getting this error:
error: format specifies type 'char *' but the argument has type
'<dependent type>' [-Werror,-Wformat]
error: use of undeclared identifier 'word'
Even if I try to initialize a char * variable "word", some other error just keeps popping up. Maybe I don't fully understand how fscanf works, could anyone provide some clearance?
How can I make the above program compile?

Answer 1

Because you are using C, this answer does not care about infamous "buffer overflow error" but please keep in mind that.
You need to declare 'word' variable before you use 'fscanf'. It looks like...
const size_t MAX_WORD_LEN=256;
char word[MAX_WORD_LEN];
then, you can.
while (fscanf(file, "%s", word) != EOF)
{
}
Here, the maximum 'word' length is 255 characters (without terminating NULL character). So in your file one single word length cannot be over 255 characters (in most cases, it should be fine).
The whole program most likely be as follow:
#include <stdio.h>
const char* const usage_msg = "Usage: program_name input-file\nInput file contains words in English or some languages. \n";
const char* const fopen_err = "\nUnable to open file: ";
const size_t MAX_WORD_LEN = 256;
int main(int argc, char *argv[]) {
if (argc != 2) {
fprintf(stderr, "%s", usage_msg);
return -1;
}
else {
/* if argv[1] contains something that is not supposed to be, it will be infamous buffer overflow. */
/* any validation on argv[1] is welcomed here */
FILE *pf = fopen(argv[1], "r");
char word[MAX_WORD_LEN];
if (pf == NULL) {
fprintf(stderr, "%s%s", fopen_err, argv[1]);
return -2;
}
/* overflow can be avoided by specifying width 255 to %s */
while (fscanf(pf, "%255s", word) != EOF) {
printf("%s\n", word);
}
}
return 0;
}