Thread: Whats wrong with this code?

It has many compilation errors.

Code:

foo.c: In function ‘importFile’:
foo.c:19:29: error: ‘fpin’ undeclared (first use in this function)
         fgets(content, len, fpin);
                             ^
foo.c:19:29: note: each undeclared identifier is reported only once for each function it appears in
foo.c:19:15: warning: passing argument 1 of ‘fgets’ from incompatible pointer type [-Wincompatible-pointer-types]
         fgets(content, len, fpin);
               ^
In file included from foo.c:1:0:
/usr/include/stdio.h:622:14: note: expected ‘char * restrict’ but argument is of type ‘double *’
 extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
              ^
foo.c:20:20: warning: passing argument 1 of ‘sscanf’ from incompatible pointer type [-Wincompatible-pointer-types]
         if (sscanf(content, "%lf", &input) == 1)
                    ^
In file included from /usr/include/features.h:367:0,
                 from /usr/include/stdio.h:27,
                 from foo.c:1:
/usr/include/stdio.h:448:12: note: expected ‘const char * restrict’ but argument is of type ‘double *’
 extern int __REDIRECT_NTH (sscanf, (const char *__restrict __s,
            ^

You're trying to use content as your input buffer for chars, and your output buffer for converted data.

fscanf - C++ Reference

Debugging is essential knowledge

Debugging code for absolute beginners - Visual Studio | Microsoft Docs

First thing I see wrong is that you have the following code:

Code:

    if(fp == NULL)
    {
        printf("ERROR");
        fclose(fp);
        return -1;
    }

This code is incorrect because if fp == NULL, you DO NOT want to call fclose(fp) because that would mean you are trying to close a file handle which isn't even open to begin with... You're trying to close a NULL file handle... Undefined behavior.

Second issue is that you are improperly using fscanf as pointed out above. You are specifying two areas of memory that you want fscanf() to read bytes into but you're only providing one format string. It's like doing this:

Code:

printf("My name is: %s\n", name, some_int);

That usage is incorrect because there is no format specifier for some_int here and in your case, you have no format specifier for the content variable. It just seems you are totally misunderstanding and misusing fscanf() here. What are you trying to accomplish? Are you trying to read a bunch of doubles from a file into a buffer in memory? If so, this aint the way to do it. You could use fread() to do that.