Compilation on Linux - In function '_start': (.text+0x20): undefined reference to 'main'

I want to compile a series of cpp files on Linux. Using CentOS 7, in the Konsole, I type "g++ -std=c++11 main.cpp canvas.cpp patch.cpp utils.cpp", and I get an error:

/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status

Could anyone tell me how to solve this?