fread/fwrite实现复制功能

Posted 2020-10-08

1.  fread/fwrite实现复制功能

#include <stdio.h>
#include <stdlib.h>

#define BUFFSIZE  4096

//执行: ./a.out file1 file2
//功能： 将file1的内容读取出来，写入file2,即复制 
int main(int argc,char *argv[])
{
    char buffer[BUFFSIZE];
    FILE *pRead,*pWrite; //读文件指针 写文件指针 
    int n;

    //检测是否输入file1和file2
    if(argc!=3)
    {
        printf("main option error!\n");
        return -1;
    }

    pRead = fopen(argv[1],"r"); //只读 文件必须已存在
    if(!pRead)
    {
        printf("fopen argv[1] error!\n");
        return -1;
    }

    pWrite = fopen(argv[2],"w"); //只写 若文件不存在，则创建
    if(!pWrite)
    {
        printf("fopen argv[2] error!\n");
        return -1;
    }

    //从pRead指向文件读取字符入buffer
    while( (n= fread(buffer,sizeof(char),sizeof(buffer),pRead))>0 )
    {
        //检测从buffer写入pWrite指向文件的字符数，是不是等于读取字符数
        if( fwrite(buffer,sizeof(char),n,pWrite)!=n )
        {
            printf("fwrite error!\n");
            return -1;
        }
    }

    if(n<0) //fread返回值<0,说明fread读取失败
    {
        printf("fread error!\n");
        return -1;
    }

    //复制结束后，要关闭文件
    fclose(pRead);
    fclose(pWrite);

    return 0;
}