C / C++ / MFC

struct foo {
    short s;
    double d;
};

_Flaviu wrote:

do you suggest me another safe method to compare structs ? A little code sample will be great !

struct foo
{
    short s;
    double d;

    bool equals( struct foo f )
    {
        // this is not the preferred method for comparing floating-point values (but that's not the point)
        return (this->s == f.s) && (this->d == f.d);
    }
};

David Crow wrote:

bool equals( struct foo f )
{
// this is not the preferred method for comparing floating-point values
return (this->s == f.s) && (this->d == f.d);
}

$ cat ex.c
#include <stdio.h>

int main()
{
    double d = 0.0;
    const double one = 1.0;

    for(size_t i = 0; i < 100; ++i)
        d += 0.01;

    // we would expect d now to be 1.0, but ...

    printf("d = %8.6f\n", d);    // output looks like 1.000000
    printf("d == 1.0 => %d\n", d == one);  // but comparison fails
    printf("1.0 - d = %g\n", one -d);  // there's a very small diff btwn d and 1.0

    return 0;
}
$ ./ex
d = 1.000000
d == 1.0 => 0
1.0 - d = -6.66134e-16
$ 

struct foo {
   short s;
   double d;
   char str[24];
};

int compare_foo(const struct foo *f1, const struct foo *f2)
{
    int retval;

    if( (retval =  f1->s - f2->s) != 0)
        return retval;

    if( (retval = f1->d - f2->d) != 0)
         return retval;

    return strcmp(f1->str, f2->str);
}

MyDoc.obj : error LNK2019: unresolved external symbol _function1 referenced in function "public: int __thiscall CMyDoc::SomeMethod
MyDoc.obj : error LNK2019: unresolved external symbol _function2 referenced in function "public: int __thiscall CMyDoc::SomeMEthod