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.