How to get ASCII code for characters from a text file? - c

Question

Update, Hello guys Thank you all for the help, my initial approach was wrong and I did not use ASCII codes at all.
Sorry for the late replay I had a half-day off today and made a new post for the complete code
there is no errors but the prgram is not working proberly ( this is an update of old post )
I wrote the program, and it is working with no errors But it is not giving me the results I wanted
My only problem is when I read a character how to check its ASCII and store it.
#include <stdio.h>
#include <string.h>
int main()
{
char dictionary[300];
char ch, temp1, temp2;
FILE *test;
test=fopen("HW2.txt","r");
for(int i=0;i<2000;i+=1)
{ ch=fgetc(test);
printf("%c",ch);
}
}

Answer 1

If we are talking about plain ASCII, values goes from 0 to 127, your table shoud look like:
int dictionary[128] = {0};
Regarding your question:
how to check its ASCII and store it
Consider a char being a tiny int, they are interchangeable and you don't need any conversion.
fgetc wants an int in order to handle EOF, and trying to read 2000 characters from a file containing less than 2000 bytes can have very bad consequences, to read the whole file:
int c;
while ((c = fgetc(test)) != EOF)
{
if ((c > 0) && (c < 128))
{
dictionary[c]++;
}
}
for (int i = 1; i < 128; i++)
{
if (dictionary[i] > 0)
{
printf("%c appeared %d times\n", i, dictionary[i]);
}
}
EDIT:
Rereading, I see that you want to store words, not chars, ok, then it's a bit more difficult but nothing terrible, do not limit yourself to 300 words, use dynamic memory:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
// A struct to hold the words and the
// number of times it appears
struct words
{
size_t count;
char *word;
};
int main(void)
{
FILE *file;
file = fopen("HW2.txt", "r");
// Always check the result of fopen
if (file == NULL)
{
perror("fopen");
exit(EXIT_FAILURE);
}
struct words *words = NULL;
size_t nwords = 0;
char *word = NULL;
size_t nchars = 1;
size_t i;
int c;
// while there is text to scan
while ((c = fgetc(file)) != EOF)
{
if (isspace(c))
{
if (word != NULL)
{
// Search the word in the table
for (i = 0; i < nwords; i++)
{
// Found, increment the counter
if (strcmp(word, words[i].word) == 0)
{
words[i].count++;
free(word);
break;
}
}
// Not found, add the word to the table
if (i == nwords)
{
struct words *temp;
temp = realloc(words, sizeof(*temp) * (nwords + 1));
if (temp == NULL)
{
perror("realloc");
exit(EXIT_FAILURE);
}
words = temp;
words[nwords].word = word;
words[nwords].count = 1;
nwords++;
}
// Prepare the next word
word = NULL;
nchars = 1;
}
}
else
{
char *temp;
temp = realloc(word, nchars + 1);
if (temp == NULL)
{
perror("realloc");
exit(EXIT_FAILURE);
}
word = temp;
word[nchars - 1] = (char)c;
word[nchars++] = '\0';
}
}
for (i = 0; i < nwords; i++)
{
printf("%s appeared %zu times\n", words[i].word, words[i].count);
free(words[i].word);
}
free(words);
fclose(file);
return 0;
}

Answer 2

In C, characters are, essentially, their ASCII code (or rather, their char or unsigned char value). So once you read a character, you have its ASCII code already.
However, fgetc() doesn't always return the character it read for you; it may fail, for which reason it returns an int, not an unsigned char, which will be -1 in case of failure.
So:
You need to define an int variable to take the result of fgetc().
If it's not EOF, you can cast the result back into a unsigned char. That's your character, and it's ASCII value, at the same time.
PS - I'm ignoring non-ASCII characters, non-Latin languages etc. (But C mostly ignores them in its basic standard library functions too.)