overloading >> operator for user defined string class - c++

Question

Question
The problem is that i am trying to get user input using insertion operator and initialising the value thechars, to allocate the size to thechars i need the length of input, how do i get it?? And initialise in insertion operator.
Main problem is with insertion operator.
When i run the program it shows the segmentation fault,
plz help
class string1
{
private:
int len;
char *thechars;
//friend ostream& operator<<(ostream&,string1&);##
//friend istream& operator>>(istream&,string1&);##
public:
//string1() :len(0),thechars(NULL){}
string1()
{
thechars = new char[1];
thechars[0] = '\0';
len=0;
// cout << "\tDefault string constructor\n";
// ConstructorCount++;
}
};
// this is the insertion operator i use
istream& operator>>(istream& in, string1& tpr)
{
in >> tpr.thechars;
//tpr.thechars[i+1]='\0';
return in;
}
//this one is the extraction operator
ostream& operator<<(ostream& out,string1& prt)
{
for(int i=0;i<prt.len;i++)
out<<prt.thechars[i];
return out;
}
// main function##
string1 str;
cout << "enter first string" << endl;
cin >> str;
cout << str << endl;

Answer 1

If in is a file input stream, you can do the following:
in.seekg(0, ios::end);
length = in.tellg();
in.seekg(0, ios::beg);
The other option is reading the input stream char by char and double the size of thechars each time it's exhausted. First, introduce one more variable to store the currently allocated size of the buffer --- allocSize. After that update the constructor and operator<< as follows.
Constructor:
string1()
{
allocSize = 1; // initially allocated size
thechars = new char[allocSize];
thechars[0] = '\0';
len=0;
}
Input operator:
istream& operator>>(istream& in, string1& tpr)
{
char inp;
while (in.get(inp)) {
// end-of-input delimiter (change according to your needs)
if (inp == ' ')
break;
// if buffer is exhausted, reallocate it twice as large
if (tpr.len == tpr.allocSize - 1) {
tpr.allocSize *= 2;
char *newchars = new char[tpr.allocSize];
strcpy(newchars, tpr.thechars);
delete[] tpr.thechars;
tpr.thechars = newchars;
}
// store input char
tpr.thechars[tpr.len++] = inp;
tpr.thechars[tpr.len] = '\0';
}
}
But the best option is to use std::string as a type for thechars. Do you really need all this manual memory handling?

Answer 2

Instead of giving the in a char* give it a regular string. Then you can extract the data yourself.
istream& operator>>(istream& in, string1& tpr)
{
string temp;
in >> temp;
tpr.len = temp.length + 1;
tpr.thechars = new char[tpr.len];
tpr.thechars[temp.length] = '\0';
strcpy(tpr.thechars, &temp[0], tpr.len);
return in;
}

Answer 3

you wrote
in>> tpr.thechars; // where thechars="\0";
You allocated only one byte, but i guess you are input string with more bytes.
I think error here.