See what the preprocessor is doing

Is there anyway to see wha开发者_Python百科t you code looks like after the preprocessor has done all the substitutions?

---

For gcc just use the -E switch

gcc -E

-E Stop after the preprocessing stage; do not run the compiler proper. The output is in the form of preprocessed source code, which is sent to the standard output.

---

That depends on your compiler. With gcc, you would use:

gcc -E source.c

---

Just a note about system headers (eg <stdio.h>): they are a pain when preprocessed.

gcc -E -nostdinc file.c or cpp -nostdinc file.c will not include expansion of system headers.

---

As an alternative to gcc-E, you can run cpp on your file.

---

Eclipse C++ IDE (CDT) has Macro Exploration control, which can be used for:

• Obtaining final macro expansion
• Looking through expansion process step-by-step

This is called Macro Exploration control.