C语言实现cp命令

C语言实现cp命令

#include<stdio.h>

int main(int argc,char * argv[])
{
  if (argc != 3)
  {
    printf("err ./a.out src dst\n");
    //如果参数不足三个，提示
  }
  //1.打开文件，源文件只读，复制出的新文件只写
  FILE *rfp = fopen(argv[1],"r");
  FILE *wfp = fopen(argv[2],"w");

  //2.从源文件读取多长就拷贝到新文件多长，直到结束
  int ret,i;
  char a[1024*4];
  while(1)
  {
    ret = fread(a,1,sizeof(a),rfp);
    if (ret == 0)
    {
      break;
    }
    fwrite(a,1,ret,wfp); 
  }
  //3.关闭文件
  fclose(rfp);
  fclose(wfp);
}