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Jogofus
Asked: 2020-04-05 06:39:29 +0800 CST 2020-04-05 06:39:29 +0800 CST

Difference String and StringStream

  • 772

I'm browsing the sstream library and I've come across stringstream. Googling I come to the conclusion that it is the same as string, but I can't understand it.

As I understand it, it is to create a string and use it as "cin" to concatenate?

#include <string>       // std::string
#include <iostream>     // std::cout
#include <sstream>      // std::stringstream

int main () {

  std::stringstream ss;

  ss << 100 << ' ' << 200;

  int foo,bar;
  ss >> foo >> bar;

  std::cout << "foo: " << foo << '\n';
  std::cout << "bar: " << bar << '\n';

  return 0;
}
c++

4 Answers

  1. Roughly speaking, a stringstreamis basically a buffer in memory that pretends to behave like a file. Simple and easy.

    It allows the same operations that a stream would allow , but it is not tied to any physical device ; all operations are performed in memory, using a string as a store .

    While a stream does not allow access to the underlying physical device, a stringstream does allow access to the stream it uses as a buffer , via the operations

    td::basic_string<CharT,Traits,Allocator> str() const;

    to get a copy of the buffer , and

    void str(const std::basic_string<CharT,Traits,Allocator>& new_str);

    to establish it ourselves.

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  2. Best Answer

    Streams are output and/or input buffers. Through them, a more or less unified interface is presented that allows you to access different data sources in a homogeneous way.

    You can use an output stream to store data in a file, to write that same information to the screen, or to output it to the printer, and the same is true for input streams .

    stringstreamit is a stream that works on an internal buffer. It does not write to files or read from keyboards. What you send to that stream ends up in memory. What is it for? Generally for internal uses.

    The class stringinstead physically represents a character string and its interface is designed to store and manage character strings.

    Some differences between both classes:

    • stringyou don't have the insert/remove operator overloaded. If it's not a buffer, it doesn't need to behave like one.
    • stringit is not capable of converting native types.
    • stringstreamdoes not have iterators. A buffer is a store of information, to use it first you have to unpack it. This feature prevents it from being used directly with the vast majority of STL functions.
    • stringstreamdoes not support explicit resizing of its internal buffer.
    • You cannot directly dump the contents of stringstreaminto another buffer. To do this you have to extract its content (for example using the toString()) method.
    • The utilities of iomanipare applicable with stringstreambut not with string.
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  3. The stringstreamare primarily used for formatting operations on strings, just as fstreams are for files.

    You can use all the functors that iostreams have to manipulate the stream such as input/output numbers ( std::hex, std::scientific, etc...), strings ( std::quoted), padding (std::setw, std::setfill), location settings ( .imbue(), std::put_money), etc.

    In other words, if iostreamtogether with its overloads of operator<</>>s it is the C++ alternative of printf, fstreamit is of fprintf, and stringstreamit is of sprintf, as well as type safe and with much more comfortable syntax, as well as iterable ( std::istream_iteratorand std::ostream_iterator, to be able to use streams as if were containers).

    • 3 
  4. include<sstream>
include <iostream>
include<string>
using namespace std;


struct profesor{
   string nombreCompleto;
   string carrera;
   string dni;
   int edad;
};

/*

    cout << "Enter title: ";
    getline (cin,films[n].title);
    cout << "Enter year: ";
    getline (cin,mystr);
    stringstream(mystr) >> films[n].year;
*/





int main(){
    
profesor pn[3];
    string strEdad;

    for(int i=0;i<3;i++){
        cout<<"Ingresar nombre completo"<<endl;
        getline(cin,pn[i].nombreCompleto);
        //cin.getline(pn[i].nombreCompleto,50);
        cout<<endl;
        cout<<"Ingresar carrera"<<endl;
        getline(cin,pn[i].carrera);
        cout<<endl;
        cout<<"Ingresar DNI"<<endl;
        getline(cin,pn[i].dni);
        cout<<endl;
        cout<<"Ingresar EDAD"<<endl;
        getline(cin,strEdad);
        stringstream(strEdad) >> pn[i].edad;
        cout<<endl;
    }

    for(int j=0;j<3;j++){
        cout<<pn[j].nombreCompleto<<"\t"<<pn[j].carrera<<"\t"<<pn[j].dni<<"\t<<pn[j].edad<<endl;
    }


}
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