fscanf

[azioupos]

Is there any way to store the value of the fscanf(file,"%i",&x)?
In my case is 5 and I want to store it in a variable!

[LB]

Do you want to store the return value or some other value? Your example seems to read into a variable called 'x'.

[azioupos]

The return value of fscanf(file,"%i",&x) is 5. And I want to store 5 into i. But doing this: i = fscanf(file,"%i",&x) returns 1, which is maybe the 1st line.
Did I give you to understand what I want to do or are you still confused with my question?

[LB]

How do you know the return value is 5 if when you assign it to i, i becomes 1? Are you certain you mean 'return value' and not the value read into x?

[azioupos]

Hmmm sorry maybe I meant this. The first line of my file is 5. And I want to read it and store it in a variable! Sorry I did not give you right instructions...

[LB]

The code you provided reads 5 into the variable named x, then. Maybe you wanted to replace x with i?

[18hRX9L8]

When you assign:
i=fscanf(),
it returns the number of variables found.

For example:
fscanf(file,"%d%d%d%d%20",...),
it will return 5.

Another example:
fscanf(file,"%d%d%d%c",...),
and the file is fomatted incorrectly (like 5 3 instead of 5 3 2)
then fscanf will return the number of variables that were found,
so 2.

[azioupos]

Thanks! Is there any way to take the value of the line? In example if my line contains only the number 5 to take it and store it in a variable?

[LB]

The code in your very first post in this thread does that, thought you may want %d and not %i

[azioupos]

It does not work even with this way...

[keskiverto]

What does not work?

Why do you use fscanf in the first place? istream has operator >> for int.

[Duthomhas]

Guys, OP is newbie who has been given assignment to work with a function that is confusing to begin with.

@azioupos
There are several things to think about.

1) A function (like fscanf()) returns a value. What that value is depends on the function. In fscanf()'s case, it returns the number of things successfully read from file.

2) A function may have input arguments. These are things you pass to the function to tell it what to do. In this case, the first argument is the file to manipulate (a FILE* obtained from something like fopen()).

The second argument is a list of the things you want to read from the file. In your case, you want to read an integer, so you tell it by saying "%d" (or "%i").

3) A function may have output arguments. These are things that the function will modify. The &x is the output argument. fscanf() will put the integer it reads from the file into the integer variable named 'x'.

So:

FILE* f;  /* This is the variable we'll use to access a file. */
int x;    /* This is the variable that will hold the value we will read from the file. */
int n;    /* This is the variable that will hold the number of items read from the file. */

f = fopen( "fooey.txt", "r" );  /* Associate f with the file "fooey.txt" */

if (f == NULL)  /* Make sure to check that the file could be opened */
{
  puts( "Hey, I could not open the file \"fooey.txt\"" );
  return 1;
}

n = fscanf( f, "%d", &x );  /* Attempt to read an integer from the file and put its value in x. */

/* n now has a value of 0 if no integer could be read from the file; */
/* n has a value of 1 if an integer was successfully read from the file. */
if (n != 0)
{
  printf( "%s %d\n", "Yay, the integer read from the file was ", x );
}
else
{
  puts( "The file did not have an integer as the first thing in the file." );
}

Hope this helps.

[edit] Oh yeah, don't forget to look at the documentation for fscanf()
http://www.cplusplus.com/reference/cstdio/fscanf/?kw=fscanf