.size main,.Lfe1-main 

  .ident "GCC: (GNU) 2.95.3 20010315 (release)" 

  

 The %esp, %ebp etc are registers. For example, %esp is the Stack Pointer - it points to the base(?) of the current process's memory stack. The first "movl" copies the value in %esp into %ebp, then the "subl" subtracts 24 off %esp, so that the stack has grown by 24 bytes. The next "movl" copies the value 5 into stack, 4 bytes below end of the stack. This address is where the variable i is being stored, so all accesses to i in the C code become references to this memory location in assembler. As you can see, explaining what assembler is doing line-by-line is tediously boring. Instead of doing i*3, it does i+(i+i). That's the "addl" and "leal" instructions. Below that, it puts some pointers (to printf's arguments) on the stack and calls printf, which gets it's arguments off the stack. This is how programmers used to write code. Early versions of [Unix] were written in assembler - when BellLabs got new machines, they re-wrote their operating system for the new machine code, until they re-wrote it in [C] in 1973.