Basic File I/O

[GaitBait]

Hi guys! I'm pretty new to C and I'm a bit confused about the File I/O stuff.

I'm trying to scan a word from a file. I can tell something is wrong with my code but I'm not sure whether it is the fscanf format or what.

char word; //word that will be read from the file


	FILE *ifp = fopen( "myFile.txt", "r" ); //open myFile to read


	if (ifp == NULL ) //if file doesn't exist
	{
		printf( "File does not exist\n" );


		return -1; //return code
	}


	while (ifp == fopen( "myFile.txt", "r") != EOF)
	{
		fscanf(" %c", word);
	}

Also, if I want to scan a word from a file, would I use %c or %s ?

[nonpuz]

You would (ideally) use fgets. But yes, a literal "word" (delimited by whitespace) could be read from a file pointer, using %s. If you wanted to read a line of text, with whitespace in it, you would have to do some tricks with %[] or simply use fgets() as I suggest.

[GaitBait]

I want the file to read just a word, not a sentence. So fscanf can't be used for this at all ?

[nonpuz]

Your loop should be controlled by fscanf() or fgets(). You are calling fopen() in your loop repeatedly which makes no sense

You want to read one singular word? If so then why are you running fscanf() in a loop? All you need is fopen(); fscanf(fp, "%s", string); fclose(); there you read 1 word.

As I said of course you CAN use fscanf(), but the recommend way is to use fgets() and sscanf() to read out from the buffer whatever it is you want (one word per line, or whatever). That way you are processing the whole file instead of leaving garbage in the buffer for your next read, which is what fscanf() is gonna do.

[GaitBait]

Ohh okay. SO something like

fgets(str, 10, fp)

would read a word from a file ? And no loop would be needed.

EDIT:

and if I wanted to print the word it read?
for example:

printf("The word is %s.", ________);

What would be placed in the blank ?

[Adak]

Hi guys! I'm pretty new to C and I'm a bit confused about the File I/O stuff.

I'm trying to scan a word from a file. I can tell something is wrong with my code but I'm not sure whether it is the fscanf format or what.

char word; //word that will be read from the file


	FILE *ifp = fopen( "myFile.txt", "r" ); //open myFile to read


	if (ifp == NULL ) //if file doesn't exist
	{
		printf( "File does not exist\n" );


		return -1; //return code
	}


	while (ifp == fopen( "myFile.txt", "r") != EOF)
	{
		fscanf(" %c", word);
	}

Also, if I want to scan a word from a file, would I use %c or %s ?

You see the problem with your while () loop? You would be trying to open a file, over and over, with each iteration, and fopen() never returns EOF, anyway, so it's an endless loop.

fopen returns either an address, (pointer), or NULL, never EOF.

char word[50]; //word that will be read from the file

FILE *ifp = fopen( "myFile.txt", "r" ); //open myFile to read

if (ifp == NULL ) //if file doesn't exist
{
	printf( "File does not exist\n" );

	return -1; //return code
}


while ((fscanf( "%s ",word)) > 0)
{
	printf(" %s", word);
}

The only problem with the above changes is that fscanf() is notoriously fickle, and likely to find something it doesn't like in the file being read.

Whereupon it will quit!

So changing this to use fgets() is a very worthwhile thing to do. The C Tutorial link at the top of the web page (near the center), will show you how to do that.

[GaitBait]

I understand now, thank you so much!