Parallel Computing for Data Science

Appendix C

Introduction to C for R

Programmers

The C language is quite complex, and C++ is even more so. The goal of

this appendix is to give a start at a reading ability in the C language for

those familiar with R.

C.0.1 Sample Program

// Learn . c

// in p ut s 5 numbers from the keyboard ,

// sq u a re s and p r i n t s them

// i n c l u d e d e f i n i t i o n s needed for sta ndard I /O

#include <s t d i o . h>

// f u n c t i o n to square the e lements o f an a r r a y x ,

// o f l e n g t h n , in−p l a c e ; both arguments a r e o f

// i n t e g e r

int sq r ( int ∗x , int n ) {

// a l l o c a t e space for an i n t e g e r i

int i ;

// for loop , i = ...