C Primer Plus, Fourth Edition

First Steps

The compiler has to put a program through some translation phases before jumping into preprocessing. The compiler starts its work by mapping characters appearing in the source code to the source character set. This takes care of multi-byte characters and trigraphs—character extensions that make the outer face of C more international. (Section VII, “Universal Character Names” gives an overview of these extensions.)

Second, the compiler locates each instance of a backslash followed by a newline character and deletes them. That is, two physical lines like

printf("That's wond\
erful!\n");

are converted to a single logical line:

printf("That's wonderful\n!");

Note that in this context, “newline character” means the character produced ...