Intel XENIX 286 Programmers Guide (86) - Tenox.tc

cc: C Compiler XENIX Programming
Creating Progra ms from C Source Files
The cc command is normally used to create executable programs from C language
source files. A file's contents are identified by the file name extension. C source files
must have the extension ".c".
The cc command can create executable programs only from source files that make up a
complete C program. In XENIX, a complete program must have one (and only one)
function named "main". This function becomes the entry point for program execution.
The "main" function may call other functions as long as they are defined within the
program or are part of the C standard library. The standard C library is described in the
XENIX 286 C Library Guide.
Compiling a C Source File
You can compile a C source file by giving the name of the file when you invoke the cc
command. The command compiles the statements in the file, then copies the
executable program to the default output file a.out.
To compile a source program, type
cc filename
where filename is the name of the file containing the program. The program must be
complete, that is, it must contain a "main" program function. It may also contain calls
to functions explicitly defined by the program or by the standard C library.
For example, assume that the following program is stored in the file named main.c.
#include
main ()
{
intx,y;
}
scanf( "%d %d", &x, &y);
pri ntf(" %d\n", x + y);
To compile this program, type
cc main.c
The command first invokes the C preprocessor, which adds the statements in the file
/usr/include/stdio.h to the beginning of the program. It then compiles these statements
and the rest of the program statements. Next, the com mand links the program with the
standard C library, which contains the object files for the scanf and printf functions.
Finally, it copies the program to the file a.out.
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