Question

This is a very simple question and I feel stupid for asking it, but I am pressed for time and I need to figure it out 🙂

I just need to know how to make a string that contains text and other variables. For instance in Java I can just do this:

String someString;

for(int i = 0; i>10; i++){

someString = ("this text has printed " + i + " times"); //how do I create this line in C++?

System.out.println(someString);

i++;

}

EDIT 4:

Ok, Rahul G’s answer below works pretty good, and the program compiles and ok, but when I run it instead of getting the string I want for the file name, I get a bunch of numbers. For instance: << "frame " << i << " .jpg" creates: “013679000.jpg” instead of “frame 0.jpg” like I want. Any thoughts?

for(int i = 0; frames; i++)
{  
  frame = cvQueryFrame(capture); 
  std::string s = static_cast<std::ostringstream &>(std::ostringstream() << argv[1] <<  i << " .jpg").str(); 
  cvSaveImage(s.c_str(), frame);
} 

Answer 1

Java:

int i = 5;
double d = 2.23606798;
String s = "Square root of "+i+" is "+d;

C++:

int i = 5;
double d = 2.23606798;
std::ostringstream oss;
oss << "Square root of " << i << " is " << d;
std::string s = oss.str();
// If you need C style string...
char const *s0 = s.c_str();

Please note that the std::ostringstream class resides in <sstream> header.

Edit:

Your code (corrected):

for(int i = 0; frames; i++) { 
  frame = cvQueryFrame(capture);
  std::ostringstream oss;
  oss << "frame " << i << " .jpg";
  cvSaveImage(oss.str().c_str(), frame);
}