Handling strings in C + + Sstream

C + + introduces Ostringstream, Istringstream, StringStream these three classes, to use them to create an object must include <sstream> this header file.

The Istringstream constructor is as follows:
Istringstream::istringstream (string str);
Its function is to read the characters from the String Object str, the StringStream object can bind a line of strings, and then separate the line with a space delimiter.

Let's separate a string by dividing it with a space.

#include <iostream>#include<sstream>#include<string>intMain () {std::stringstr ="I am Coding ..."; Std::istringstream is(str);  Do{std::stringsubstr;  is>>substr; Std::cout<< substr <<Std::endl; }  while( is); return 0;}

Program output

I

Am

Coding

...

In addition, vector can also be used to achieve

#include <vector>#include<iostream>#include<string>#include<sstream>using namespacestd;intMain () {stringStr"I am Coding ..."); stringbuf;     StringStream SS (str); Vector<string>VEC;  while(SS >>buf) Vec.push_back (BUF);  for(vector<string>::iterator iter = Vec.begin (); Iter! = Vec.end (); ++ITER) {cout<< *iter <<Endl; }    return 0;}

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Using templates in type conversions

You can easily define a function template to convert an arbitrary type to a specific target type. For example, you need to convert various numeric values, such as int, long, double, and so on, to a string, using the to_string () function with a string type and an arbitrary value of T as the argument. The to_string () function converts t to a string and writes to result. Use the STR () member function to get a copy of the stream's internal buffer:

template<class t>void to_string (string & result,const t& T) {   ostringstream oss; // Create a Stream    oss<<t; // Pass the value to the stream    result=oss.str (); // gets the converted character to go and writes it to result}

In this way, you can easily convert a number of values to a string:

To_string (s1,10.5);//double to String

To_string (s2,123);//int to String

To_string (s3,true);//bool to String

You can further define a generic transformation template for conversions between any type. The function template convert () contains two template parameters Out_type and In_value, which is the function of converting in_value values into Out_type types:

template<class Out_type,class in_value>out_type CONVERT (const In_value & t) {   stringstream stream;   Stream<<t; // passing values to the stream    out_type result; // The conversion results are stored here    Stream>>result; // write value to result     return  result;}

This uses convert ():

Double D;

string salary;

String s= "12.56";

D=convert<double> (s);//d equals 12.56

Salary=convert<string> (9000.0);//salary equals "9000"

Handling strings in C + + Sstream