看C++Primer的时候看到的，然后去百度了一下；

比较明白的解释：

1、区别在于:
\n只代表换行的转义字符
endl除了代表换行，还紧跟着清出缓冲槽2、接下来我们看一下具体内容的辨析：
要明白\n和endl的区别，首先要明白一个概念：
输出流。
目前输出流的类型很多，有对文件作为目标输出的，有对显示屏（Console间接输出）进行输出的。也有输出到其他抽象结构的。cout的意思是console-output：控制台输出.
但是它的机制还远没有我们想的那么简单，<<后面跟着写什么就直接输出到屏幕什么？
不是这样的。就拿cout<<"Hi,zw.\n"<<endl;来说，cout代表后面的内容输出到控制台的一个缓冲槽，而不是控制台（黑屏幕的那个）.缓冲槽在什么情况下会把缓冲槽的内容输出到控制台的【屏幕界面】呢？
当遇到endl或者其他fflush之类的命令或函数时，缓冲槽里的内容会按照顺序输出到控制台，再由控制台进行转意字符的识别打印。endl和\n的区别是：\n在控制台里被翻译为【换行】
endl在控制台里也被翻译成【换行】但endl还在缓冲槽这个部分有个功能：清槽，把缓冲槽里的内容输出到控制台。为什么平时几乎没有任何区别呢？
因为缓冲槽即使不用endl,只要遇到另一行表达式，一般也会自动清槽。

只要程序不蹦，还是没什么区别的，万一程序崩溃，\n可能会留在缓冲区里；

贴两段代码（及其汇编）：

#include <iostream>
using namespace std;
int main()
{cout<<"a"<<endl;return 0;
}

   .file   "\316\264\303\374\303\3731.cpp"
.lcomm __ZStL8__ioinit,1,1.def  ___main;    .scl    2;  .type   32; .endef.section .rdata,"dr"
LC0:.ascii "a\0".text.globl   _main.def   _main;  .scl    2;  .type   32; .endef
_main:
LFB971:.cfi_startprocleal   4(%esp), %ecx.cfi_def_cfa 1, 0andl  $-16, %esppushl -4(%ecx)pushl   %ebp.cfi_escape 0x10,0x5,0x2,0x75,0movl %esp, %ebppushl %ecx.cfi_escape 0xf,0x3,0x75,0x7c,0x6subl   $20, %espcall   ___mainmovl $LC0, 4(%esp)movl   $__ZSt4cout, (%esp)call __ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKcmovl    $__ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_, (%esp)movl    %eax, %ecxcall  __ZNSolsEPFRSoS_Esubl   $4, %espmovl    $0, %eaxmovl    -4(%ebp), %ecx.cfi_def_cfa 1, 0leave.cfi_restore 5leal  -4(%ecx), %esp.cfi_def_cfa 4, 4ret.cfi_endproc
LFE971:.def ___tcf_0;   .scl    3;  .type   32; .endef
___tcf_0:
LFB981:.cfi_startprocpushl  %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl  %esp, %ebp.cfi_def_cfa_register 5subl   $8, %espmovl    $__ZStL8__ioinit, %ecxcall  __ZNSt8ios_base4InitD1Evleave.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc
LFE981:.def __Z41__static_initialization_and_destruction_0ii;   .scl    3;  .type   32; .endef
__Z41__static_initialization_and_destruction_0ii:
LFB980:.cfi_startprocpushl  %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl  %esp, %ebp.cfi_def_cfa_register 5subl   $24, %espcmpl   $1, 8(%ebp)jne  L4cmpl  $65535, 12(%ebp)jne L4movl  $__ZStL8__ioinit, %ecxcall  __ZNSt8ios_base4InitC1Evmovl    $___tcf_0, (%esp)call   _atexit
L4:leave.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc
LFE980:.def __GLOBAL__sub_I_main;   .scl    3;  .type   32; .endef
__GLOBAL__sub_I_main:
LFB982:.cfi_startprocpushl  %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl  %esp, %ebp.cfi_def_cfa_register 5subl   $24, %espmovl   $65535, 4(%esp)movl $1, (%esp)call  __Z41__static_initialization_and_destruction_0iileave.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc
LFE982:.section .ctors,"w".align 4.long   __GLOBAL__sub_I_main.ident  "GCC: (GNU) 4.8.1".def    __ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc;   .scl    2;  .type   32; .endef.def  __ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_;    .scl    2;  .type   32; .endef.def  __ZNSolsEPFRSoS_E;  .scl    2;  .type   32; .endef.def  __ZNSt8ios_base4InitD1Ev;   .scl    2;  .type   32; .endef.def  __ZNSt8ios_base4InitC1Ev;   .scl    2;  .type   32; .endef.def  _atexit;    .scl    2;  .type   32; .endef

#include <iostream>
using namespace std;
int main()
{cout<<"a"<<"\n";return 0;
}

   .file   "\316\264\303\374\303\3732.cpp"
.lcomm __ZStL8__ioinit,1,1.def  ___main;    .scl    2;  .type   32; .endef.section .rdata,"dr"
LC0:.ascii "a\0"
LC1:.ascii "\12\0".text.globl _main.def   _main;  .scl    2;  .type   32; .endef
_main:
LFB971:.cfi_startprocpushl  %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl  %esp, %ebp.cfi_def_cfa_register 5andl   $-16, %espsubl  $16, %espcall   ___mainmovl $LC0, 4(%esp)movl   $__ZSt4cout, (%esp)call __ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKcmovl    $LC1, 4(%esp)movl   %eax, (%esp)call    __ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKcmovl    $0, %eaxleave.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc
LFE971:.def ___tcf_0;   .scl    3;  .type   32; .endef
___tcf_0:
LFB976:.cfi_startprocpushl  %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl  %esp, %ebp.cfi_def_cfa_register 5subl   $8, %espmovl    $__ZStL8__ioinit, %ecxcall  __ZNSt8ios_base4InitD1Evleave.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc
LFE976:.def __Z41__static_initialization_and_destruction_0ii;   .scl    3;  .type   32; .endef
__Z41__static_initialization_and_destruction_0ii:
LFB975:.cfi_startprocpushl  %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl  %esp, %ebp.cfi_def_cfa_register 5subl   $24, %espcmpl   $1, 8(%ebp)jne  L4cmpl  $65535, 12(%ebp)jne L4movl  $__ZStL8__ioinit, %ecxcall  __ZNSt8ios_base4InitC1Evmovl    $___tcf_0, (%esp)call   _atexit
L4:leave.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc
LFE975:.def __GLOBAL__sub_I_main;   .scl    3;  .type   32; .endef
__GLOBAL__sub_I_main:
LFB977:.cfi_startprocpushl  %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl  %esp, %ebp.cfi_def_cfa_register 5subl   $24, %espmovl   $65535, 4(%esp)movl $1, (%esp)call  __Z41__static_initialization_and_destruction_0iileave.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc
LFE977:.section .ctors,"w".align 4.long   __GLOBAL__sub_I_main.ident  "GCC: (GNU) 4.8.1".def    __ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc;   .scl    2;  .type   32; .endef.def  __ZNSt8ios_base4InitD1Ev;   .scl    2;  .type   32; .endef.def  __ZNSt8ios_base4InitC1Ev;   .scl    2;  .type   32; .endef.def  _atexit;    .scl    2;  .type   32; .endef

本弱汇编还在学= = 所以很多看不懂=- =~

等能看懂了，再回来研究研究