Unix Programming - A question about weak external symbols

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A question about weak external symbols

Zheng Da

2006-08-20, 1:21 am

The book <linkers and loaders> gives the example of printf when it
describe weak external symbols. But I don't understand well how weak
external symbols work in printf.
Does it means if there is "%f" in the first parameter of printf,
fltused will be called and floating point routines will be linked?
I don't understand that if there's a reference to fltused, the floating
point routines are linked.
Is fltused a function?
If it is, it seems that fltused has some codes that can link the
floating point routines.
Anyway, I am quite confused.