三种IO库实现文件的拷贝

read（）write（）实现文件copy

#include<stdio.h>

#include<string.h>

#include<sys/stat.h>

#include<fcntl.h>

#include<unistd.h>

#define MAX 128

int main(int argc, const char *argv[])

{
if(argc<3)
{
printf("too few arguments\n");
return 0;
}
int fdread,fdwrite;
if((fdread=open(argv[1],O_RDONLY))<0)
{
perror("cannot open file");
return 0;

}
if((fdwrite=open(argv[2],O_WRONLY|O_CREAT|O_TRUNC,0664))<0)
{
perror("too few arguments");
return 0;
}
char buf[MAX];
int len;
int count=0;
while((len=read(fdread,buf,MAX))>0)
{
count+=len;
write(fdwrite,buf,len);
}

    printf("%d\n",count);
close(fdread);
close(fdwrite);
return 0;

}

gets（）puts（）实现文件拷贝

#include<stdio.h>

#include<string.h>

#define MAXSIZE 32

int main(int argc, const char *argv[])

{

    if(argc<3)
{
printf("too lew argument\n");
return 0;
}
FILE *fpread ,*fpwrite;
if((fpread=fopen(argv[1],"r"))==NULL)
{
perror("cannot open file1");
return 0;
}
char str[MAXSIZE];

if((fpwrite=fopen(argv[2],"w"))==NULL)
{
perror("cannot open file2");
return 0;
}

    while(fgets(str,MAXSIZE,fpread)!=NULL)
{
fputs(str,fpwrite);
}

    fclose(fpread);
fclose(fpwrite);
return 0;

}

fread()fwrite()实现文件copy

#include<stdio.h>

#define MAX 64

int main(int argc, const char *argv[])

{
if(argc<3)
{
printf("too few arguments\n");
return 0;
}
FILE *fpread,*fpwrite;
char str[MAX];
int n; 
if((fpread=fopen(argv[1],"r"))==NULL)
{
perror("cannot open file");
return 0;
}
if((fpwrite=fopen(argv[2],"w"))==NULL)
{
perror("cannot open file");
return 0;
}
while((n=fread(str,1,MAX,fpread))>0)
{
fwrite(str,1,n,fpwrite);
}
fclose(fpread);
fclose(fpwrite);

return 0;

}