Sams Teach Yourself C in 21 Days

DAY 19

WEEK 3

Exploring the C Function

Library

As you’ve seen throughout this book, much of C’s power comes from the func-

tions in the C standard library. In today’s lessons, you’ll explore some of the

functions that don’t fit into the subject matter of other days. Today you will

learn about

• Mathematical functions


• Functions that deal with time


• Error-handling functions


• Functions for searching and sorting data

Mathematical Functions ......................................................................................

The C standard library contains a variety of functions that perform mathemati-

cal operations. Prototypes for the mathematical functions are in the header file

math.h. The math functions all return a type double. For the trigonometric

functions, angles are expressed in radians rather than degrees, which you may

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