Experiment Q&A............

When I compiled the lookup program using MySQL connector C++ statically:

Q: what if I am confronted with "ld: can not found lm "?

A: The reason is that 'ld' can not find the static version of 'libm.a' within the default position.

     So I need to install it in Fedora using yum: "sudo yum install glibc-static". This should solve the 'lm' problem.

Q: what if I am confronted with message: "undefined reference to 'pthread_self' and so on...."?

A: The problem is that the pthread library can not be found. Just direct the g++ the location of it by append "-lpthread" at the end.

Q: What is the command that I used to compile the program and link against the static library?

A: Like this: "g++ -static -o <dst> <src> /usr/local/lib/libmysqlcppconn-static.a /usr/local/mysql/lib/libmysqlclient.a -lpthread".

Q: When using the static library, sometimes there is a strange message pop out: can not found lc ?
A: Because the static version of glibc is not installed by default, we need to install by ourself:
        sudo yum install glibc-static

Parsing Long Options

Find this topic in DOCUMENT of GNU C library: libc

http://www.gnu.org/software/libc/manual/   From page 633

Here I conclude some useful tips:

== return values of getopt():

• successful
• a character (the option name without argument)
• a character (the option name), a pointer to char (char *optarg: argument)
• failed
• '?' (not included in options OR missing argument) (int optopt keeps the character)
• -1 complete

== return values of getopt_long ():

• successful
• short_options
• (same with getopt())
• long_options
• content of val (flag = NULL) (Tips, put corresponding short option char in val)
• 0 (flag != NULL, put content of val into *flag)
• (same with above two) (with argument are stored in optarg)
• failed
• (same with getopt())
• -1 complete

    PS: indexptr record the index of the options in array of struct option.