Improve company productivity with a Business Account.Sign Up

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1256
  • Last Modified:

Cant compile using g++ -O2 or -O3

Hi

I can run my code using O mode but when I try to use the compilers advanced optimization settings I get whole load of funny errors.  Any suggestions?

Thanks

Niall
This isn't all of the errors, just the first few!
 
 
pclxb10>make
g++ -o2 csvdemo main.cpp csvparser.cpp
csvdemo: In function `_start':
(.text+0x0): multiple definition of `_start'
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crt1.o:(.text+0x0): first defined here
csvdemo:(.rodata+0x0): multiple definition of `_fp_hw'
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crt1.o:(.rodata+0x0): first defined here
csvdemo: In function `_fini':
(.fini+0x0): multiple definition of `_fini'
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crti.o:(.fini+0x0): first defined here
csvdemo:(.rodata+0x4): multiple definition of `_IO_stdin_used'
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crt1.o:(.rodata.cst4+0x0): first defined here
csvdemo: In function `__data_start':
(.data+0x0): multiple definition of `__data_start'
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crt1.o:(.data+0x0): first defined here
csvdemo:(.rodata+0x8): multiple definition of `__dso_handle'
/usr/lib/gcc/i386-redhat-linux/4.1.2/crtbegin.o:(.rodata+0x0): first defined here
csvdemo: In function `_init':

Open in new window

0
duncan54747
Asked:
duncan54747
  • 2
1 Solution
 
Infinity08Commented:
>> g++ -o2 csvdemo main.cpp csvparser.cpp

Did you mean :

        g++ -o csvdemo main.cpp csvparser.cpp -O2

The -o flag is for renaming the executable (to csvdemo in this case).
The -O2 flag sets the optimization level (notice the upper case O).
0
 
Infinity08Commented:
The reason for all those errors, is because the compiler compiled the two .cpp files, and then the linker tried to link them together with the csvdemo executable that was there from an earlier build. Obviously these contain the exact same symbols.
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now