lexer questions

• Is it necessary to undef macros within function?
• How to access/print the auxiliary vector entry in main?
• How do I echo string with bash command more in Perl?
• Why does this ptrace program say syscall returned -38?
• What's the difference between open and sysopen in Perl?
• How to implement a generic macro in C?
• How to initialize a union? [duplicate]

lexer answers