E

Syntax

    -E 

Purpose
Runs the source files named in the compiler invocation through the preprocessor. The -E option calls the preprocessor directly as /usr/ibmcxx/exe/xlCcpp.

Notes
The -E and -P options have different results. When the -E option is specified, the compiler assumes that the input is a C or C++ file and that the output will be recompiled or reprocessed in some way. These assumptions are:

• Original source coordinates are preserved. This is why #line directives are produced.
• All tokens are output in their original spelling, which, in this case, includes continuation sequences. This means that any subsequent compilation or reprocessing with another tool will give the same coordinates (for example, the coordinates of error messages).

The -P option is used for general-purpose preprocessing. No assumptions are made concerning the input or the intended use of the output. This mode is intended for use with input files that are not written in C or C++. As such, all preprocessor-specific constructs are processed as described in the ANSI C standard. In this case, the continuation sequence is removed as described in the "Phases of Translation" of that standard. All non-preprocessor-specific text should be output as it appears.

Using -E causes #line directives to be generated to preserve the source coordinates of the tokens. Blank lines are stripped and replaced by compensating #line directives.

The line continuation sequence is removed and the source lines are concatenated with the -P option. With the -E option, the tokens are output on separate lines in order to preserve the source coordinates. The continuation sequence may be removed in this case.

The -E option overrides the -P, -o, and -qsyntaxonly options, and accepts any file name.

If used with the -M option, -E will work only for files with a .C (C++ source files), .c (C source files), or a .i (preprocessed source files) filename suffix. Source files with unrecognized filename suffixes are treated and preprocessed as C files, and no error message is generated.

Comments are replaced in the preprocessed output by a single space character. New lines and #line directives are issued for comments that span multiple source lines, and when -C is not specified. Comments within a macro function argument are deleted.

The default is to preprocess, compile, and link-edit source files to produce an executable file.

Example
To compile myprogram.c and send the preprocessed source to standard output, enter:

xlC myprogram.c -E

If myprogram.c has a code fragment such as:

#define SUM(x,y) (x + y) ;
int a ;
#define mm 1 ; /* This is a comment in a
                  preprocessor directive */
int b ;        /* This is another comment across
                  two lines */
int c ;
               /* Another comment */
c = SUM(a, /* Comment in a macro function argument*/
        b) ;

the output will be:

#line 2 "myprogram.c"
int a;
#line 5
int b;
 
int c;
 
c =
(a + b);

List of Compiler Options and Their Defaults
Options that Specify Compiler Output