Help with a 'undefined symbol' error in a class's set function

[fsefsef23]

I'm finding myself stuck trying to simply get a userInfo class's sets to work, but every time I try and compile with simple code like this in my application file:

userInfo stuff;

stuff.setId("test");

It gives me one of those 'undefined symbol' errors and references to the userInfo::setId function:

Undefined first referenced
symbol in file
userInfo::setId(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)/var/tmp//cc1wjEkh.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status

The sets are implemented as follows in my implementation file:

void userInfo::setId(string anId) { id = anId;}
void userInfo::setPassword(string passwd) {password = passwd;}

Not sure if I'm missing some vital or obvious factor about the userInfo sets. Any help would be MUCH appreciated.

[NathanOliver]

Could you post the deceleration for your userInfo class? Also please use code tags.

[Moschops]

void userInfo::setId(string anId) { id = anId;}

What's id? Is that definitely a member of the userInfo class