How can I see the assembly code for a C++ program?

In GCC/G++, compile with -S. That will output a something.s file with the assembly code.

Edit: If you want the output to be in Intel syntax (which is IMO, much more readable, and most assembly tutorials use it), compile with -masm=intel.


In Visual Studio;

  1. set a breakpoint
  2. run the program until it stops at the breakpoint
  3. rightclick on the sourcecode and pick "show dissasembly"

For gcc/g++

gcc -save-temps -fverbose-asm prog.c

This will generate prog.s with some comments on variables used in every asm line:

    movl    $42, -24(%ebp)  #, readme
    movl    -16(%ebp), %eax # pid, pid
    movl    %eax, 4(%esp)   # pid,
    movl    $.LC0, (%esp)   #,
    call    printf  #

Ask the compiler

If you are building the program yourself, you can ask your compiler to emit assembly source. For most UNIX compilers use the -S switch.

  • If you are using the GNU assembler, compiling with -g -Wa,-alh will give intermixed source and assembly on stdout (-Wa asks compiler driver to pass options to assembler, -al turns on assembly listing, and -ah adds "high-level source" listing):

    g++ -g -c -Wa,-alh foo.cc

  • For Visual Studio, use /FAsc.

Peek into a binary

If you have a compiled binary,

  • use objdump -d a.out on UNIX (also works for cygwin),
  • dumpbin /DISASM foo.exe on Windows.

Use your debugger

Debuggers could also show disassembly.

  • Use disas command in GDB.
    Use set disassembly-flavor intel if you prefer Intel syntax.
  • or the disassembly window of Visual Studio on Windows.