Mail Archives: djgpp/1995/10/03/03:06:55
On Mon, 2 Oct 1995, Chris A. Rodgers wrote:
> Hi all! In short, I installed djgpp and it compiled hello.c from the
> samples directory just fine, but when I try a simple c++ program, I get
> the following error:
>
> myfirst.cc(.text+0x2e): undefined reference to `cout'
> myfirst.cc(.text+0x33): undefined reference to `ostream::operator<<(char const *
> )'
> myfirst.cc(.text+0x40): undefined reference to `cout'
> myfirst.cc(.text+0x45): undefined reference to `ostream::operator<<(char const *
> )'
>
> [snip]
>
> E:\DJGPP\SRC\cis_230\testbed1>gcc -v myfirst.cpp
Short answer: add `-lgpp -lm' to the end of your command line.
Long answer: you did download the FAQ (faq102.zip), but probably didn't
try to search it. The FAQ has this entry at section 8.8:
8.8 Q: When I compile my program, the linker complains about mathematical
functions, although I did #include <math.h>.
Q: The linker complains it cannot find cprintf function.
--> Q: Why do I get so many unresolved symbols when linking C++ programs?
A: By default, gcc instructs the linker to only look in two libraries:
libgcc.a and libc.a. Some functions aren't included there, so the
linker can't find them. For math functions, like sin() and exp(),
append ``-lm'' to the gcc command line; for pc-specific
functions, like cputs() and cprintf() append ``-lpc''; to use C++
classes append ``-lgpp''. GPL library routines, like obstack and
regex packages are in libgpl.a library; append ``-lgpl'' to use
them.
Note that some C++ classes use math routines, so the -lm should
be given after the -lgplus.
There are more sections after this which deal with related problems;
please read them and save yourself a lot of pain.
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