Apply string functions to char

[pucivogel]

Can i apply find_first_of ,substr,istringstream and make_pair to a char array?

[Fbody]

You definitely can't use find_first_of and substr. They are members of the std::string class, and as such must be called using either the "dot" or "arrow" operator on a std::string object or pointer to std::string respectively. This means you won't even be able to get to them from a C-style string (char array).

The constructor for an istringstream has a reference to a std::string as an argument, so you may be able to create one from a char array because you can construct an std::string from a char array, but I have my doubts. Whatever you do to the stream probably won't be reflected in the array though.

The make_pair function is a templatized function, which means it can accept anything as an argument. You can use a char array as an argument.

But you want to know the best way to find out? Try it yourself. There's precious few better ways to learn than through experimentation.

[mrnutty]

Umm what exactly do you have in mind? Your questions isn't to clear for me.

[pucivogel]

Hey there,i have this code. It shows no error in the console but it shows a debug error,and in the output only the first "for"

#include <iostream>
	#include <string>
	
	using namespace std;
        int main ()
	{  const int polynomsize=5;
	   string sub[polynomsize];
	   string coefficient[polynomsize];
	  string str ="2.4x^4 - 1.2x^3 + 6x^2 + 4.1x + 9.2";
	  size_t found;
 
	  found=str.find_first_of("+-");
	   
	   sub[0]=str.substr(0,found);
	  cout<<"sub1"<<"  "<<sub[0]<<endl;
	  while (found!=string::npos)
	  { for (int i=1;i<=polynomsize;i++)
	 
	         { int a=found;
           found=str.find_first_of("+-",found+1);
	           sub[i]=str.substr(a,found-a);
	           cout<<"sub"<<i+1<<"  "<<sub[i]<<endl;
	     
	  }

	     
	  }
	 
	    for (int j=0;j<=polynomsize;j++)
		{ size_t foundx;
		foundx=sub[j].find_first_of("x");
		coefficient[j]=sub[j].substr(0,foundx);
		cout<<coefficient[j];
		}
	 
	  return 0;
	}

[Moschops]

I haven't read your example code as I'm in a rush, but if you ever have a char array, and you want to carry out string operations on it, you can turn it into a string, carry out your operations, and then turn it back to a char array.

#include <string>
#include <cstring>
int main()
{

char aCharArray[] = "Hello World"; 
std::string aString(aCharArray);
// Carry out string operations....
aString.insert(4,"X");
char* cstr = new char [aString.size()+1];
strcpy (cstr, aString.c_str());
std::cout << cstr;

// Ignore memory leaks, I'm not being paid enough to worry about them :p

}

Output:

HellXo World