Write INT to config file

Write INT to config file

MacGyver1979

Member #14,135

March 2012

Hello together,

i have a question regarding the configfile.
I want to write some INT values in it, but the value should be a const char*.
I'm working with ALLEGRO 5.0.4.

I think there are two solutions for it,
1. convert int to const char* (not knowing)
2. there is a function to write a int value to the config file (not knowing)

Maybe anyone can explain me the "right" way with an short example?

With best regards

MacGyver

William Labbett

Member #4,486

March 2004

Write yourself a function

int write_int_to_config(int i)
{
   char s[30];
  
   // convert i to string - that's a tricky job but not too hard.

   // use al_write_to_config( (const char *)s, .... ) or whatever the function is
 
}

gnolam

Member #2,030

March 2002

snprintf()
strtol()

--
Move to the Democratic People's Republic of Vivendi Universal (formerly known as Sweden) - officially democracy- and privacy-free since 2008-06-18!

MacGyver1979

Member #14,135

March 2012

My solution

#SelectExpand
  1const char* convertInt(int number)
  2{
  if (number == 0)
      return "0";
  string temp="";
  string returnvalue="";
  while (number>0)
  {
      temp+=number%10+48;
      number/=10;
  }
  for (int i=0;i<temp.length();i++)
      returnvalue+=temp[temp.length()-i-1];
 14
      const char *c = returnvalue.c_str();
  return c;
 17}

Is there a better solution for it?

Arthur Kalliokoski

Second in Command

February 2005

Click on the links gnolam posted.

They all watch too much MSNBC... they get ideas.

MacGyver1979

Member #14,135

March 2012

Hello Arthur Kalliokoski,

and what's wrong with my posted solution?

Greats MacGyver

gnolam

Member #2,030

March 2002

For a C++ solution, use stringstreams.

[EDIT]

MacGyver1979 said:

and what's wrong with my posted solution?

Two major things from a quick skim:

Won't handle negative integers
returnvalue goes out of scope, so the pointer that .c_str() returns becomes invalid as soon as that function returns.

--
Move to the Democratic People's Republic of Vivendi Universal (formerly known as Sweden) - officially democracy- and privacy-free since 2008-06-18!

Arthur Kalliokoski

Second in Command

February 2005

MacGyver1979 said:

and what's wrong with my posted solution?

I didn't check it at all, but reinventing the wheel is usually a waste of time and often leads to bugs.

They all watch too much MSNBC... they get ideas.

MacGyver1979

Member #14,135

March 2012

Hello,

thanks for that quick response.

Won't handle negative integers
returnvalue goes out of scope, so the pointer that .c_str() returns becomes invalid as soon as that function returns.

Negative integers are not given, but i understand you.

I'm not so confirm with

snprintf()
strtol()

can anyone explane me with a little example?

Greats MacGyver

LennyLen

Member #5,313

December 2004

MacGyver1979 said:

can anyone explane me with a little example?

Those are C functions. Since you are using C++, you should use stringstreams as gnolam said.

something like:

#include <sstrream>
...
    stringstream str;
    str << int_value_I_want_to_convert;
    al_set_config_value(config_file, section, key, (str.str()).c_str());
    str.str("");

MacGyver1979

Member #14,135

March 2012

Ok works for me.
Thanks

#SelectExpand
 1#include <sstream>
 2
 3    stringstream str;
 4    str << 50;
 5    const char *c = str.str().c_str();

William Labbett

Member #4,486

March 2004

Part of being a newb (I know this from experience) is that you find yourself doing things the hard way due to lack of experience. Then you're reluctant to do things the easy way because it means all your previous hard work was a waste of time.
Anyway, here's the easy way :

I should have posted what Gnolam posted.

#SelectExpand
  1int write_int_to_config(ALLEGRO_CONFIG *cp, const char *section, const char *key, int i)
  2{
  3   char s[30];
  4  
  5
  6   if( snprintf( s, 30, "%d", i) == 0)
  7   {
  8      return 1; //error
  9   }
 10   else
 11   {
 12      al_set_config_value( cp, section, key, (const char *) s);
 13      return 0; //okay
 14   }
 15}

Arthur Kalliokoski

Second in Command

February 2005

William Labbett said:

you find yourself doing things the hard way due to lack of experience.

Been there, done that.

They all watch too much MSNBC... they get ideas.

William Labbett

Member #4,486

March 2004