C++ - std::string & char*

[LennonCook]

Basically, I have a very large program which is *almost* compiling: my only problems are with a line that looks like:

code:

---

std::string input = temp;

[/QUOTE]Where temp is a char* . My compiler (Borland 5) tells me "Cannot convert char* to std::string" . I've tried changing the code to be:

code:

---

std::string input(temp);

[/QUOTE]
But Borland tells me "No match for string::string(char *)".
But when I try this silly little block of code that I found elsewhere (in response to another problem related to the same classes), it compiles without so much as even a warning.

code:

---

#include <cstring>

#include <string>

#include <iostream>

using namespace std;



int main(){

  char   *t;

  char    u[50];

  char   *v;

  string  w;

  string  s;



  t = "this string is t, it is a very long string. much longer than 30 chars.\n";

  strcpy(u, "this is u, it is also a fairly long string.\n");

  v = strdup(u);

  v[8] = 'v';

  w = "and this is string w, it's not a char array like the rest.\n";



  s  = t;

  s += u;

  s += v;

  s += w;



  delete v;

  cout << s;

}

[/QUOTE]
So, is there any rhyme or reason to Borland's complaining? And, more importantly, is there any way to fix it?

[philip]

I don't have any c++ experience (not counting nwscript [img]smile.gif[/img] ) but what I often do when I get an error I don't get is use google with the exact code of the error, except for my own constants or declarations.

When I did that with your code I got to this site, under the 'C++ has scary error messages' it looks like a similar error to the one you have. Also the description of the error is good looking at the error message you've got.

BTW and this is purely a guess at it cause as I said I don't know much about c++ but those 2 declarations look so similar I doubt they do much different things. Again I don't know about c++ but other languages have convert functions maybe you could try those (if they're in c++ of course), cause right now it looks like you're trying to declare a char* as string (also from the msg) which IMHO doesn't look very if that's possible so easy.

Why I think the other piece of code works. It looks like that piece is adding characters to a string, instead of immediately equalling a string to a char*?

[Vaskez]

Firstly, I don't think you don't need std:: in front of string if you declare "using namespace std;" at the top

code:

---

string input( temp );

[/QUOTE]seems like it should work, but according to my reference you need a const char* not a char* as the input. So you could try casting temp to a const char* first, or copying its value to an already declared const char*.

You could also try

code:

---

string input;

input = temp;

[/QUOTE]Yes, I find that it does make a difference if you declare the variable on the same line or not.

Let me know if it doesn't work, I might have some suggestions, including checking out this site:

http://www.cppreference.com/cppstrin...l#Constructors

[LennonCook]

Time for me to slap myself silly. I've been using a string class which I coded, which publically inherits from std::string . I needed to provide my own constructors, and the assignment operator is virtual. Fixed up those two problems by adding few lines to my class, and it now compiles.

I now need to test this thing very quickly because it's due on Monday. It's a CGI application, and so I need a webserver which can be set up to run a binary file server-side. Meaning, I either need someone who has such a webserver, or I need to figure out how to configure Apache... and then there's the user manual...