Why are C and C++ different even after compilation? -

i guessed still surprised see output of these 2 programs, written in c , c++, when compiled different. makes me think concept of objects still exist @ lowest level. add overhead? if impossible optimization convert object oriented code procedural style or hard do?

helloworld.c

#include <stdio.h>  int main(void) {     printf("hello world!\n");     return 0; } 

helloworld.cpp

#include <iostream>  int main() {   std::cout << "hello world!" << std::endl;   return 0; } 

compiled this:

gcc helloworld.cpp -o hwcpp.s -s -o2 gcc helloworld.c -o hwc.s -s -o2 

produced code:

c assembly

    .file   "helloworld.c"     .section    .rodata.str1.1,"ams",@progbits,1 .lc0:     .string "hello world!\n"     .text     .p2align 4,,15 .globl main     .type   main, @function main:     pushl   %ebp     movl    %esp, %ebp     andl    $-16, %esp     subl    $16, %esp     movl    $.lc0, 4(%esp)     movl    $1, (%esp)     call    __printf_chk     xorl    %eax, %eax     leave     ret     .size   main, .-main     .ident  "gcc: (ubuntu 4.4.3-4ubuntu5) 4.4.3"     .section    .note.gnu-stack,"",@progbits 

c++ assembly

    .file   "helloworld.cpp"     .text     .p2align 4,,15     .type   _global__i_main, @function _global__i_main: .lfb1007:     .cfi_startproc     .cfi_personality 0x0,__gxx_personality_v0     pushl   %ebp     .cfi_def_cfa_offset 8     movl    %esp, %ebp     .cfi_offset 5, -8     .cfi_def_cfa_register 5     subl    $24, %esp     movl    $_zstl8__ioinit, (%esp)     call    _znst8ios_base4initc1ev     movl    $__dso_handle, 8(%esp)     movl    $_zstl8__ioinit, 4(%esp)     movl    $_znst8ios_base4initd1ev, (%esp)     call    __cxa_atexit     leave     ret     .cfi_endproc .lfe1007:     .size   _global__i_main, .-_global__i_main     .section    .ctors,"aw",@progbits     .align 4     .long   _global__i_main     .section    .rodata.str1.1,"ams",@progbits,1 .lc0:     .string "hello world!"     .text     .p2align 4,,15 .globl main     .type   main, @function main: .lfb997:     .cfi_startproc     .cfi_personality 0x0,__gxx_personality_v0     pushl   %ebp     .cfi_def_cfa_offset 8     movl    %esp, %ebp     .cfi_offset 5, -8     .cfi_def_cfa_register 5     andl    $-16, %esp     pushl   %ebx     subl    $28, %esp     movl    $12, 8(%esp)     movl    $.lc0, 4(%esp)     movl    $_zst4cout, (%esp)     .cfi_escape 0x10,0x3,0x7,0x55,0x9,0xf0,0x1a,0x9,0xfc,0x22     call    _zst16__ostream_inserticst11char_traitsiceerst13basic_ostreamit_t0_es6_pks3_i     movl    _zst4cout, %eax     movl    -12(%eax), %eax     movl    _zst4cout+124(%eax), %ebx     testl   %ebx, %ebx     je  .l9     cmpb    $0, 28(%ebx)     je  .l5     movzbl  39(%ebx), %eax .l6:     movsbl  %al,%eax     movl    %eax, 4(%esp)     movl    $_zst4cout, (%esp)     call    _znso3putec     movl    %eax, (%esp)     call    _znso5flushev     addl    $28, %esp     xorl    %eax, %eax     popl    %ebx     movl    %ebp, %esp     popl    %ebp     ret     .p2align 4,,7     .p2align 3 .l5:     movl    %ebx, (%esp)     call    _znkst5ctypeice13_m_widen_initev     movl    (%ebx), %eax     movl    $10, 4(%esp)     movl    %ebx, (%esp)     call    *24(%eax)     jmp .l6 .l9:     call    _zst16__throw_bad_castv     .cfi_endproc .lfe997:     .size   main, .-main     .local  _zstl8__ioinit     .comm   _zstl8__ioinit,1,1     .weakref    _zl20__gthrw_pthread_oncepipfvve,pthread_once     .weakref    _zl27__gthrw_pthread_getspecificj,pthread_getspecific     .weakref    _zl27__gthrw_pthread_setspecificjpkv,pthread_setspecific     .weakref    _zl22__gthrw_pthread_createpmpk14pthread_attr_tpfpvs3_es3_,pthread_create     .weakref    _zl20__gthrw_pthread_joinmppv,pthread_join     .weakref    _zl21__gthrw_pthread_equalmm,pthread_equal     .weakref    _zl20__gthrw_pthread_selfv,pthread_self     .weakref    _zl22__gthrw_pthread_detachm,pthread_detach     .weakref    _zl22__gthrw_pthread_cancelm,pthread_cancel     .weakref    _zl19__gthrw_sched_yieldv,sched_yield     .weakref    _zl26__gthrw_pthread_mutex_lockp15pthread_mutex_t,pthread_mutex_lock     .weakref    _zl29__gthrw_pthread_mutex_trylockp15pthread_mutex_t,pthread_mutex_trylock     .weakref    _zl31__gthrw_pthread_mutex_timedlockp15pthread_mutex_tpk8timespec,pthread_mutex_timedlock     .weakref    _zl28__gthrw_pthread_mutex_unlockp15pthread_mutex_t,pthread_mutex_unlock     .weakref    _zl26__gthrw_pthread_mutex_initp15pthread_mutex_tpk19pthread_mutexattr_t,pthread_mutex_init     .weakref    _zl29__gthrw_pthread_mutex_destroyp15pthread_mutex_t,pthread_mutex_destroy     .weakref    _zl30__gthrw_pthread_cond_broadcastp14pthread_cond_t,pthread_cond_broadcast     .weakref    _zl27__gthrw_pthread_cond_signalp14pthread_cond_t,pthread_cond_signal     .weakref    _zl25__gthrw_pthread_cond_waitp14pthread_cond_tp15pthread_mutex_t,pthread_cond_wait     .weakref    _zl30__gthrw_pthread_cond_timedwaitp14pthread_cond_tp15pthread_mutex_tpk8timespec,pthread_cond_timedwait     .weakref    _zl28__gthrw_pthread_cond_destroyp14pthread_cond_t,pthread_cond_destroy     .weakref    _zl26__gthrw_pthread_key_createpjpfvpve,pthread_key_create     .weakref    _zl26__gthrw_pthread_key_deletej,pthread_key_delete     .weakref    _zl30__gthrw_pthread_mutexattr_initp19pthread_mutexattr_t,pthread_mutexattr_init     .weakref    _zl33__gthrw_pthread_mutexattr_settypep19pthread_mutexattr_ti,pthread_mutexattr_settype     .weakref    _zl33__gthrw_pthread_mutexattr_destroyp19pthread_mutexattr_t,pthread_mutexattr_destroy     .ident  "gcc: (ubuntu 4.4.3-4ubuntu5) 4.4.3"     .section    .note.gnu-stack,"",@progbits 

different compilers produce different code. version of gcc versus current version of gcc produce different code.

more importantly, iostream handles lot of things stdio doesn't, there's going substantial overhead. understand that, in theory, these compiled down indentical code, they're doing not technically identical.