sp1r1t@pandora:~/eva$ g++ individuals.cpp
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../lib/crt1.o: In function `_start':
../sysdeps/i386/elf/start.S:115: undefined reference to `main'
/tmp/ccZM8Jbm.o: In function `individual::operator=(individual&)':
individuals.cpp:(.text+0x33): undefined reference to `individual::size'
/tmp/ccZM8Jbm.o: In function `individual::mutation()':
individuals.cpp:(.text+0x65): undefined reference to `individual::size'
individuals.cpp:(.text+0x8b): undefined reference to `individual::number_of_colors'
/tmp/ccZM8Jbm.o: In function `individual::individual(int*, bool)':
individuals.cpp:(.text+0x104): undefined reference to `individual::size'
individuals.cpp:(.text+0x13b): undefined reference to `individual::number_of_colors'
/tmp/ccZM8Jbm.o: In function `individual::individual(int*, bool)':
individuals.cpp:(.text+0x194): undefined reference to `individual::size'
individuals.cpp:(.text+0x1cb): undefined reference to `individual::number_of_colors'
/tmp/ccZM8Jbm.o: In function `individual::individual(int*)':
individuals.cpp:(.text+0x213): undefined reference to `individual::size'
/tmp/ccZM8Jbm.o: In function `individual::recombination(individual*, individual*)':
individuals.cpp:(.text+0x23d): undefined reference to `individual::size'
individuals.cpp:(.text+0x260): undefined reference to `individual::size'
/tmp/ccZM8Jbm.o: In function `individual::individual(int*)':
individuals.cpp:(.text+0x2e9): undefined reference to `individual::size'
collect2: ld returned 1 exit status