# V1035\. Only values returned from fgetpos\(\) can be used as arguments to fsetpos\(\)\.

As defined by the C standard, calling the 'fsetpos' function with an argument obtained not by the 'fgetpos' function leads to undefined behavior\.

Consider the following example:

```cpp
int foo()
{
  FILE * pFile;
  fpos_t position;

  pFile = fopen("file.txt", "w");
  memset(&position, 0, sizeof(position));
  fputs("That is a sample", pFile);
  fsetpos(pFile, &position);
  fputs("This", pFile);
  fclose(pFile);
  return 0;
}
```

Because the value of the 'position' variable was obtained not by the 'fgetpos' function, further program execution may fail\.

Fixed code:

```cpp
int foo()
{
  FILE * pFile;
  fpos_t position;

  pFile = fopen("file.txt", "w");
  fgetpos(pFile, &position);
  fputs("That is a sample", pFile);
  fsetpos(pFile, &position);
  fputs("This", pFile);
  fclose(pFile);
  return 0;
}
```