assigning a char pointer to string value using for loop

[nokstar]

Ok, I'm a beginner, I'm trying to assign a char pointer to a string.

using:

for(int i=0;i<userin.length();i++)
        {
            
            *(isbn+i) = userin.at(i);
        }

So I've tried everything I've thought of, when userin = 1-214-02031-3, but no matter what happens I still get an output at *isbn of 1111111111111.

Any advice would be greatly appreciated.

[Duthomhas]

I don't see that code producing the problem you indicate. (Your code does have a problem, though -- it fails to null-terminate the isbn string.)

Can you give us a working example program that replicates your problem?


That said, you could use the copy() method to get the data into a c-string:

  char isbn[14];

  string userin;

  int len = (14 < userin.length()) ? 14 : userin.length();
  userin.copy( isbn, len );
  isbn[len] = '\0';

If you currently #include <cstring>, you could use strncpy() instead:

  char isbn[14];

  string userin;

  int len = (14 < userin.length()) ? 14 : userin.length();
  strncpy( isbn, userin.c_str(), len );
  isbn[len] = '\0';

It doesn't really save you anything though, and the first method avoids the additional dependency on <cstring>.

Hope this helps.