파일 복사 함수의 효율 비교
1533 단어 파일 복사
방법1: 한 글자씩 읽고 출력하기
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
int main(void){
char c;
int in, out;
in=open("file.in", O_RDONLY);
out=open("file.out", O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR);
while(read(in, &c, 1)==1){
write(out, &c, 1);
}
exit(0);
}
효율성:[lujinhong@lujinhong BeginningLinuxProgramming]$ TIMEFORAMT=""time ./a.out 0.31user 8.07system 0:08.40elapsed 99%CPU (0avgtext+0avgdata 1392maxresident)k 0inputs+9032outputs (0major+110minor)pagefaults 0swaps
방법2: 1K씩 읽고 출력하기
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#define READ_SIZE 1024
int main(void){
char c[READ_SIZE];
int in, out;
int nread;
in=open("file.in", O_RDONLY);
out=open("file.out", O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR);
while((nread=read(in, c, READ_SIZE))>0){
write(out, c, nread);
}
exit(0);
}
효율성:[lujinhong@lujinhong BeginningLinuxProgramming]$ TIMEFORAMT=""time ./a.out 0.00user 0.01system 0:00.01elapsed 92%CPU (0avgtext+0avgdata 1408maxresident)k 0inputs+9032outputs (0major+111minor)pagefaults 0swaps