Reading a file word by word with no ending chars - c

Question

I have this small program in C that reads through a file a compares word by word,
how can I assure that words like "this," won't be read as a word? I would like it to read as "this"
int main(int argc, char *argv[]) {
if(argc != 3)
{
printf("Usage: ./sw <word> <filename> \n");
exit(1);
}
char* word = argv[1];
const char* filename = argv[2];
FILE* file = fopen(filename, "r");
if(file == NULL)
{
printf("Could not open file\n");
exit(1);
}
//Assuming one word can not have more than 250 chars
char w[250], check_eof;
do
{
check_eof = fscanf(file, "%s", w);
if(strcmp(word, w) == 0)
{
printf("W : %s \n", w);
}
} while(check_eof != EOF);
fclose(file);
return 0;
}

Answer 1

You can check if a char belongs to a word like this
int c = fgetc(file);
if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
// c belongs to a word
word[n++] = c;
} else {
// end of word
if (strncmp(word, w, n) == 0) {
// word and w match!
}
}
If you #include <ctype.h>, then you can call isalpha(c) instead to test it.

Answer 2

In the code below, I use isalpha() and I copy the result string in a new buffer named res. However, this procedure can be done in-place, but I'll leave now for the sake of simplicity.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h> // for isalpha()
int main(int argc, char *argv[]) {
char* word = "this";
const char* filename = "test.txt";
FILE* file = fopen(filename, "r");
if(file == NULL)
{
printf("Could not open file\n");
exit(1);
}
//Assuming one word can not have more than 250 chars
// ATTENTION, it is 249 chars, do NOT forget of the null terminator
char w[250], res[250];
int check_eof; // should be of type int, for EOF checking
do
{
check_eof = fscanf(file, "%s", w);
// what if 'word' appears as the last word
// in the file? You should check for eof
// right after fscanf()
if(check_eof == EOF)
break;
int i = 0, j = 0;
while (w[i]) // parse what we read
{
if (isalpha(w[i]))
res[j++] = w[i]; // keep only the alphabetic chars
i++;
}
res[j] = '\0'; // it should be a null terminated string
if(strcmp(word, res) == 0) // compare to 'res' now
{
printf("W : %s \n", res);
}
} while(1); // the terminating step is inside the body now
fclose(file);
return 0;
}