fflush()

참조 : http://msdn.microsoft.com/ko-kr/library/9yky46tz.aspx

[source]

// crt_fflush.c
#include <stdio.h>

int main( void )
{
   int integer;
   char string[81];

   // Read each word as a string.
   printf( "Enter a sentence of four words with scanf: " );
   for( integer = 0; integer < 4; integer++ )
   {
      scanf( "%s", string, sizeof(string) );      
      printf( "%s\n", string );
   }

   // You must flush the input buffer before using gets. 
   // fflush on input stream is an extension to the C standard 
   fflush( stdin );   
   printf( "Enter the same sentence with gets: " );
   gets( string);
   printf( "%s\n", string );
}

//MS에서 제공한 test source를 사용햇는데 conio 헤더가 레뎃6.2버전에서는 
존재하지 않아서 약간수정하고 gets_s와 scanf_s를 각각 gets 와 scanf로 
수정해준후 진행하였다 

[디버깅] 
(gdb) disas main
Dump of assembler code for function main:
0x8048490 <main>:	push   %ebp
0x8048491 <main+1>:	mov    %esp,%ebp // SFP 
// | SFP  | RET
   ↑esp,ebp
0x8048493 <main+3>:	sub    $0x58,%esp //
// | stack [88] | SFP | RET  
          ↑esp,ebp
스택은 보통 4의배수로 할당받기 때문에 이렇게 85byte 가아닌 88byte를 
할당된다 
0x8048496 <main+6>:	push   $0x80485a0 //printf()'s string 
0x804849b <main+11>:	call   0x80483c8 <printf>// printf() call 
0x80484a0 <main+16>:	add    $0x4,%esp // calling convention 
0x80484a3 <main+19>:	movl   $0x0,0xfffffffc(%ebp)//ebp -4에 0 을
  | stack [81]|integer= 0 | SFP | RET 
                          ↑ebp,esp
0x80484aa <main+26>:	lea    0x0(%esi),%esi// NOP 
0x80484b0 <main+32>:	cmpl   $0x3,0xfffffffc(%ebp)//ebp -4 부분과
// | stack [81]| integer=0 | SFP | RET 
                           ↑ebp,esp
0x80484b4 <main+36>:	jle    0x80484b8 <main+40>// 같거나 작으면 
//main+40으로 jmp
0x80484b6 <main+38>:	jmp    0x80484e1 <main+81>//크면 main+81로
// jmp 
0x80484b8 <main+40>:	push   $0x51 //81바이트 push 
0x80484ba <main+42>:	lea    0xffffffa8(%ebp),%eax//ebp-88을eax로
0x80484bd <main+45>:	push   %eax // eax에 인자를 집어넣고 
0x80484be <main+46>:	push   $0x80485cc // 형식포멧 집어넣어주고 
0x80484c3 <main+51>:	call   0x8048398 <scanf> // scanf() call 
0x80484c8 <main+56>:	add    $0xc,%esp//calling conevntion 
0x80484cb <main+59>:	lea    0xffffffa8(%ebp),%eax // input값
0x80484ce <main+62>:	push   %eax // push 
0x80484cf <main+63>:	push   $0x80485cf //string 
0x80484d4 <main+68>:	call   0x80483c8 <printf> // printf() call 
0x80484d9 <main+73>:	add    $0x8,%esp // calling convention 
---Type <return> to continue, or q <return> to quit---
0x80484dc <main+76>:	incl   0xfffffffc(%ebp)//long형으로
//???? 
0x80484df <main+79>:	jmp    0x80484b0 <main+32>// for()로 jmp
0x80484e1 <main+81>:	mov    0x80496f0,%eax// &stdin 
0x80484e6 <main+86>:	push   %eax // push 
0x80484e7 <main+87>:	call   0x8048378 <fflush>//fflush() call 
0x80484ec <main+92>:	add    $0x4,%esp//calling convention 
0x80484ef <main+95>:	push   $0x80485e0 //printf()'s string
0x80484f4 <main+100>:	call   0x80483c8 <printf>// printf() call 
0x80484f9 <main+105>:	add    $0x4,%esp//calling convention 
0x80484fc <main+108>:	lea    0xffffffa8(%ebp),%eax //string을 입력받음
0x80484ff <main+111>:	push   %eax //push  
0x8048500 <main+112>:	call   0x8048388 <gets> //gets() call 
0x8048505 <main+117>:	add    $0x4,%esp // calling convention 
0x8048508 <main+120>:	lea    0xffffffa8(%ebp),%eax//string
0x804850b <main+123>:	push   %eax// push 
0x804850c <main+124>:	push   $0x80485cf //printf()'s string 
0x8048511 <main+129>:	call   0x80483c8 <printf>// printf() call 
0x8048516 <main+134>:	add    $0x8,%esp //calling convention 
0x8048519 <main+137>:	leave  //에필로그 
0x804851a <main+138>:	ret