What does this error mean?

[Hanna Roberts]

so im trying to run one of my functions in my program and im getting a error that I've attached below. Im not sure what it is saying or how to fix it. could someone help me?
This is the function code its referring to:

char buffer[1000];
    int i = 0;

    while(fgets(buffer,1000,fIn) != NULL)
    {
       fscanf(buffer,"%[^,],%lf,%lf,%[^,],%[^,],%[^,],%[^,]",airports[i].name, &airports[i].latitude, &airports[i].longitude,
                airports[i].city, airports[i].country, airports[i].code, airports[i].url);
    }

[Stephan van Hulst]

The error quite literally says what's wrong: as its first argument it expects a pointer to a file, but instead you have passed it an array of characters.

To read from a string, use sscanf.

[John Matthews]

Bear in mind that the last string, the URL, will include the \n added by fgets().

[Tim Holloway]

Stephan van Hulst wrote:The error quite literally says what's wrong: as its first argument it expects a pointer to a file, but instead you have passed it an array of characters.

To read from a string, use sscanf.

scanf - read and parse data from stdin
fscanf - read and parse data from a file
sscanf - parse data from a string (buffer)

printf has similar relatives.

[Hanna Roberts]

Oh ok. Thanks for the help.

[Hanna Roberts]

Wait so you said sscanf is for a string but I’m trying to making it parse each line in a file. Would it still be sscanf that I use?

[Tim Holloway]

fscanf is what you use when you want a single function to both read in a line of text and process it.

sscanf is what you use when you have already read in the line in a separate operation. Or if you got the line from a database or some other source/constructor and want to process it.

And actually, "scanf()" is just shorthand for "fscanf( stdin, ... )"

[Hanna Roberts]

oh ok I think I get it now

[Hanna Roberts]

do you know what could cause the error Illegal instruction: 4 to print?

[Stephan van Hulst]

Can you show us the latest version of your code and the full error message?

[Tim Holloway]

That sounds like the C/C++ equivalent of a NullPointerException. The "4" is often a reference to memory location (address) 4, which would not be a valid memory reference on most hardware platforms - for application programs, anyway. As to why "4" instead of "0" - well there are reasons, but they don't matter. Any memory reference down in the bottom of RAM is likely a problem.

[Hanna Roberts]

oh ok thank you. I think I was able to fix the problem