Its an easy mistake to make.
The source code is read by the compiler and it converts it to machine code. The resulting machine code is a combination of simple instructions and library files linked together. A good compiler will look for things it can simplify, for example if part of a calculation always gives the same value it will use the result directly instead of calculating it each time. Often, if the same few lines of code are repeated several times they will automatically be placed in one subroutine and called several times instead of being inserted as duplicate instructions. The linking process will also try to fit blocks of code together to find a best fit in the processor memory so small changes may have no effect or cause a complete rearrangement of the memory blocks.
It follows that you can't assume fewer lines of source code will result in smaller executable programs.
In theory, you can write all programs in 'C' on a single line although I certainly wouldn't recommend trying ! Find the best trade off between size of source code and it being logically arranged and of course be readable.
Brian.