Oracle 5.0 Reference Manual Download

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Building and Running C API Client Programs

2133

• The client application should link the C runtime statically by using the

/MT

compiler option.

If the client application is built in in debug mode and uses the static debug C runtime (

/MTd

compiler

option), it can link to the

mysqlclient.lib

static library if that library was built using the same option.

If the client application uses the dynamic C runtime (

/MD

option, or

/MDd

option in debug mode), it

must must be linked to the

libmysql.dll

dynamic library. It cannot link to the static client library.

The MSDN page describing the link options can be found here:

http://msdn.microsoft.com/en-us/

library/2kzt1wy3.aspx

Troubleshooting Problems Linking to the MySQL Client Library

Linking with the single-threaded library (

libmysqlclient

) may lead to linker errors related

pthread

symbols. When using the single-threaded library, please compile your client with

MYSQL_CLIENT_NO_THREADS

defined. This can be done on the command line by using the

-D

option

to the compiler, or in your source code before including the MySQL header files. This define should not
be used when building for use with the thread-safe client library (

libmysqlclient_r

If the linker cannot find the MySQL client library, you might get undefined-reference errors for symbols
that start with

mysql_

, such as those shown here:

/tmp/ccFKsdPa.o: In function `main':

/tmp/ccFKsdPa.o(.text+0xb): undefined reference to `mysql_init'

/tmp/ccFKsdPa.o(.text+0x31): undefined reference to `mysql_real_connect'

/tmp/ccFKsdPa.o(.text+0x69): undefined reference to `mysql_error'

/tmp/ccFKsdPa.o(.text+0x9a): undefined reference to `mysql_close'

You should be able to solve this problem by adding

-Ldir_path -lmysqlclient

at the end of your

link command, where

dir_path

represents the path name of the directory where the client library is

located. To determine the correct directory, try this command:

shell>

mysql_config --libs

The output from

mysql_config

might indicate other libraries that should be specified on the link

command as well. You can include

mysql_config

output directly in your compile or link command

using backticks. For example:

shell>

gcc -o progname progname.o `mysql_config --libs`

If an error occurs at link time that the

floor

symbol is undefined, link to the math library by adding

-lm

to the end of the compile/link line.

If you get

undefined reference

errors for the

uncompress

compress

function, add

-lz

to the

end of your link command and try again.

Similarly, if you get undefined-reference errors for other functions that should exist on your system,
such as

connect()

, check the manual page for the function in question to determine which libraries

you should add to the link command.

If you get undefined-reference errors such as the following for functions that don't exist on your system,
it usually means that your MySQL client library was compiled on a system that is not 100% compatible
with yours:

Oracle 5.0, Reference Manual

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