All of these source files can be compiled at once using only one invocation of xlC . Although more than one source file can be compiled using a single invocation of the compiler, you can specify only one set of compiler options on the command line per invocation. Each distinct set of command-line compiler options that you want to specify requires a separate invocation. By default, the xlC command preprocesses and compiles all the specified source files. The -E option preprocesses the source file, writes to standard output, and halts processing without generating an output file.
Preprocessed files are useful for checking macros and preprocessor directives.
Object Files Object files must have a .o suffix, for example, year.o. Object files, library files, and nonstripped executable files serve as input to the linkage editor. After compilation, the linkage editor links all of the specified object files to create an executable file. Assembler Files Assembler files must have a .s suffix, for example, check.s. Assembler files are assembled to create an object file.