Thread: sprintf equivalence in C++

Hi,

I was getting some help at the C forum, on converting an int to a char[]. Quzah suggested the use of sprintf, but now I have decided to implement what I am doing in C++, rather than C, and I am getting compilation errors with sprintf.

Is there an equivalent function of sprint in C++? or is there another way to approach the conversion.


I wasnt sure if I should get the post moved, a mod can merge them if they feel they should be.

Thanks.

If you decide not to use sprintf, the "other way to approach the conversion" is to use stringstreams:

Code:

#include <iostream>
#include <strstream>
using namespace std;

int main()
{
    strstream temp;
    int data = 15;
    char buffer[20];

    temp << data;     // Store int in strstream
    temp >> buffer;   // Read int value back into char buffer

    cout << buffer << endl;

    return 0;
}

Or...

Code:

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

int main()
{
    stringstream temp;
    int data = 15;
    string buffer;

    temp << data;     // Store int in stringstream
    temp >> buffer;   // Read int value back into string

    cout << buffer << endl;

    return 0;
}

Im getting a cast error, I must be calling sprintf() wrong

//funtion prototype
void Timer:rawText(GLint x, GLint y, char* s, GLfloat r, GLfloat g, GLfloat b);

int i = 10; // want that to be used in my function, need to convert it
char buf[256];

sprintf(buf, sizeof(buf), i);

And then I would use buf in my function call.

Edit:

strstream' : undeclared identifier

I included the header file, but I get the following error....

Im using Visual Studio

Yeah, you don't need the size, and you do need a format specifier. Here is a link: http://cppreference.com/stdio_details.html#sprintf

I really would recommend stringstreams with strings, though (hk_mp5kpdw's second example). That is a much less error prone solution.

Wouldn't it be better to use the ostringstream class? I think strstream is deprecated

Code:

#include <iostream>
#include <sstream>
using namespace std;

int main()
{
    ostringstream temp;
    int data = 15;
    char buffer[20];

    temp << data << flush;     // Store int into stream
    temp.str().copy(buffer, 20);   // Read int value back into char buffer
    cout << buffer << endl;
    cin.get();
    return 0;
}

Using your example:

Code:

int i = 10; // want that to be used in my function, need to convert it
char buf[256];

sprintf(buf, "%d", i);

It works the same as printf(), just outputs to a string versus the screen.