fwrite

 NAME
  fwrite - write data to a file pointer

 SYNOPSIS
  #include <stdio.h>

  size_t robjs = fwrite(buf, objsize, nobjs, fp);
  const void *buf;
  size_t objsize;
  size_t nobjs;
  FILE *fp;

 FUNCTION
  fwrite() writes the specified number of objects to a file pointer
  from the specified buffer and returns the actual number of objects
  written or 0 or -1 depending on the error.

  If the return value robjs is not equal to nobjs then a write error
  occured.

  Having two size arguments, an object size and number of objects,
  simplifies the reading of structure arrays off disk.

 NOTE
  To use fwrite to read an arbitrary number of bytes one normally
  uses the form:  r = fwrite(buf, 1, n, fp); ... i.e. n objects
  of size 1.

 EXAMPLE
  /*
   *  NOTE:   run fread() example after this one to read data back
   *      from the file
   */

  #include <stdio.h>

  #define NOBJS   15

  typedef struct {
      short   a, b, c, d;
  } MyObj;

  main()
  {
      FILE *fp;
      MyObj O;

      if (fp = fopen("T:fwrite_tmp", "wb")) {
      short n;
      for (n = 0; n < NOBJS; ++n) {
          O.a = n;
          O.b = n * 2;
          O.c = n * 3;
          O.d = n * 4;
          if (fwrite(&O, sizeof(MyObj), 1, fp) != 1) {
          puts("write error");
          exit(1);
          }
      }
      fclose(fp);
      } else {
      puts("Unable to create T:fwrite_tmp");
      exit(1);
      }
      return(0);
  }

 INPUTS
  void *buf;          buffer to copy data from
  size_t objsize;     size of one object
  size_t nobjs;       number of objects to write
  FILE *fp;           file pointer to read objects from

 RESULTS
  size_t robjs;       number of objects actually written (0 or EOF on error)

 SEE ALSO
  fread, fopen, fclose, fseek, ftell, rewind