3

I have tried this 

cout. setf(ios::oct, ios::basefield) ;
cout << 79 << endl;

It works but using manipulator setiosflags

cout << setiosflags (ios::oct) << 79 << endl;

It doesn't work, there's still 79 printed at the screen.
Although I heard setiosflags is the alternative of `setf.

Then how to print out the decimal number as octal number using setiosflags?

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2
  • what is the meaning of "it doesn't work" ? If you get compiler errors you have to include them in the question Commented Aug 16, 2019 at 11:18
  • 1
    I've changed my mind and voted to reopen the question. I think it's useful for future research about the problem. Commented Aug 16, 2019 at 11:44

4 Answers 4

Reset to default
6

Keep It Simple and Stupid (or shortly KISS):

std::cout << std::oct << 79 << std::endl;

std::oct is a syntactic sugar for str.setf(std::ios_base::oct, std::ios_base::basefield), which (as you noticed) is one of the ways to force stream to print integral values in octal notation.

See it online

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4

You need to reset the flags first using the std::resetiosflags:

#include <iostream>
#include <iomanip>

int main()
{
  int x = 42;
  std::cout << std::resetiosflags(std::ios_base::dec)
            << std::setiosflags(std::ios_base::hex | std::ios_base::showbase)
            << x;
}

The | std::ios_base::showbase part is optional.

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1 Comment

Can you briefly explain @Ron why do we need to use resetiosflags
0

you can use also 

 printf("%o",79);
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3 Comments

The OP clearly asks about c++ I/O manipulators. Your answer doesn't cover that.
@πάνταῥεῖ With that approach, my answer should be downvoted as well, because it doesn't use std::setiosflags
@Yksisarvinen But your answer shows a way how to use I/O manipulators.
0

Just try this your issue will be resolve. cout << hex << 79; cout << oct << 79;

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