How do I use %d or %c... in Cout instruction?

Question

I am studying C and C++ and would like to understand how I could transform this code written with printf() in cout, or how to use the functions %d %x %c, etc. in the cout.

int main()
{ 
printf("i make %d program \n" , 2)
system("PAUSE");
return 0;
}

Answer 1

You must study stream of io and their handlers. Example:

#include <iostream>
using namespace std;

int main() {
    auto x = 65;
    cout << "i make " << x << " program\n";
    cout << "i make " << hex << x << " program " << endl;
    cout << "i make " << (char)x << " program " << endl;
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

The printf() works with conventions where it replaces a part of the text with something that comes as a parameter, and what’s used there as placeholder determines what to do. C++ uses data flows that line up and produce a result. So he assembles each element and the first item is who receives everything that comes after. The cout is the output to the console.

Obviously knowing the value it’s best to put it all together in one string only. It’s only legal to use this when you don’t know what you’ll get in the placeholder, then in this case we will understand that this x would be a value that comes externally.

The second example sends to a handler before sending to the exit and the hex changes the number output format to hexadecimal, such as %x would.

I also used \n and endl, even though both end a line has differences between them (see link above).

The third example had to convert from number to char at hand. Good C compilers configured appropriately require the same. Note that the stream doesn’t care about the guy who comes. If the guy has a stream configured it will know what to do. All basic language types have, and all types should have some operator stream configured, it’s like a ToString() of other languages.

In the posted documentation there are several other very useful modifiers for data formatting. You can even create your own with a little more knowledge.

Answer 2

• Well, first of all, you need to know that C++, it’s different, it’s not defined by output shapers as %d, %x, or things like that. Instead, you use only the variable and the modelling commands.

Example

int n = 5; Cout<< n;

You print the value 5...

For hexadecimal printing, Cout << Hex << n;

And so on, there are several modelers for C++, you can learn them, on youtube, researching workbook of c++, pdf’s, basic courses..