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A problem. When using assembly language to call the C language function

I use assembly language to call the C language function.And I have a problem.

main.s

Code:

.section .data

a:

        .int 10

b:

        .int 20

.section .text

.globl main

.type main,@function

main:

        movl $a,%eax

        movl $b,%ebx

        pushl %ebx

        pushl %eax

        call _swapint

        movl $1,%eax

        movl $0,%ebx

        int $0x80

pro.c

Code:

#include<stdio.h>

int _swapint(int *a,int *b)

{

int c;

printf("!!!");

c=*a;

*a=*b;

*b=c;

printf("success!");

return 0;

}

I am sure that the value of a and b have been swapped,but I can't see any output! I can't understand.

thx.

when I use

Code:

puts("success");

It's OK!
but,why??

It's because puts adds a newline, and stdout is line buffered, so you don't see anything until you output a newline.

Quote:

Originally Posted by Guttorm (Post 5248436)

It's because puts adds a newline, and stdout is line buffered, so you don't see anything until you output a newline.

thank you very much！！