system call to copy files [closed]

Closed. This 开发者_开发百科question does not meet Stack Overflow guidelines. It is not currently accepting answers.

---

Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist

Closed 9 years ago.

Improve this question

how to create a system call on c++ that copies one file to the other files?

---

There is no yet file-system library in the standard library of C++, so you have several choices :

• use platform-specific API : you'll use non-portable function specific to your OS but that will do what you want;
• use a (cross-platform) library : a good library is boost::filesystem but I'm not sure it allows for moving/copying files, just check the functions in the doc;
• use std::system() to call OS-specific command-line commands : std::system("copy fileA.txt fileB.txt" or similar should work on windows, it's platform specific and can be dangerous from a security point of view, but it works.

---

You can use the std::system function

#include <cstdlib>
...
std::system("cp from.txt to.txt");

---

This code copies a file in C. You can modify it to copy to a number of files.

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

int main(int argc, char *argv[])
{
  FILE *from, *to;
  char ch;


  if(argc!=3) {
    printf("Usage: copy  \n");
    exit(1);
  }

  /* open source file */
  if((from = fopen(argv[1], "rb"))==NULL) {
    printf("Cannot open source file.\n");
    exit(1);
  }

  /* open destination file */
  if((to = fopen(argv[2], "wb"))==NULL) {
    printf("Cannot open destination file.\n");
    exit(1);
  }

  /* copy the file */
  while(!feof(from)) {
    ch = fgetc(from);
    if(ferror(from)) {
      printf("Error reading source file.\n");
      exit(1);
    }
    if(!feof(from)) fputc(ch, to);
    if(ferror(to)) {
      printf("Error writing destination file.\n");
      exit(1);
    }
  }

  if(fclose(from)==EOF) {
    printf("Error closing source file.\n");
    exit(1);
  }

  if(fclose(to)==EOF) {
    printf("Error closing destination file.\n");
    exit(1);
  }

  return 0;
}

Blatently stolen from source

---

Be carefuly using the "system" function, this is like copying the file from a DOS window, you are basically bypassing Windows.