This question already has answers here:
Setting width in C++ output stream
(3 answers)
Closed 9 years ago.
I know how to set field width but only applying to the first element in the stream.
For example.
cout << setw(5) << left << '1' << '2';
produces
1 2
and
cout << setw(5) << left << '1' << '2' << '3';
produces
1 23
How can I use the iomanip library to set the field width so that it applies to all elements
producing
1 2 3
instead of writing setw(5) twice like below:
cout << setw(5) << left << '1' << setw(5) << left << '2' << '3';
Unfortunately, no. You must use setw() before almost every output operation. The problem is that operator<< effectively calls setw(0) after the output, thus you need to set width again. See here for a full list of operations that reset field width.
Note: setw is just a wrapper around width(), so using the latter won't help.
Related
This question already has answers here:
Undefined, unspecified and implementation-defined behavior
(9 answers)
Closed 23 days ago.
It seems that member function clear() of string does remove its content, but the removed contents still can be accessed by operator[] . Here's the example that makes me confused.
#include <iostream>
using namespace std;
int main()
{
string input = "Weird";
cout << "Your Input: " << input << "\n";
input.clear();
cout << "Your Input: " << input << "\n";
cout << "Your Input: " << input[0] << input[1] << input[2] << input[3] << input[4] << '\n';
return 0;
}
The results are:
Your Input: Weird
Your Input:
Your Input: eird
Why this is happenning? If example above is normal, what should I do to completely remove its content? (accessing by input[1] should be '\000')
Accessing elements of a string after calling the method clear invokes undefined behavior.
It seems in your case the class std::string uses its internal buffer defined within the class itself for short strings.
After the call of clear the class just set the first character of the buffer with the terminating zero character '\0;.
To check that string was cleared just output its length as for example
std::cout << input.length() << '\n';
In most of my code, the in.peek() works as getting whatever the next char is supposed to be. However, when it is reading some symbols, it returns a number rather than the char, and I am not sure how to fix it to get the symbol I want.
The text file reads:
print "Good morning!!";
but during the " char I use file.peek() to read the next symbol is a ; to change the state of my switch, but it comes out as a number instead of the symbol.
This is how I am trying to print, I even created a temp char and set it to in.peek(), but that just comes out as a blank space.
char temp = in.peek();
cout<<"hit " << ch << " "<< in.peek()<<" "<<temp << endl;
The output is: "hit " 10 "
With the last bit being a blank space. Does anyone know how I can fix this so I get the ;?
peek returns an int (to account for possibility of eof()). To make sure cout recognizes it as a char, you can cast it (though this will produce incorrect values if you did hit EOF), e.g.:
cout << "hit " << ch << " " << static_cast<char>(in.peek()) << " " << temp << endl;
I am attempting format the output of a file using setw with no success. I understand that my output is shifting based on the character length of the variable before it, however I do not know how to change my code so that each row will print independent of the row before it. (Please see image link)
Due to the word "Swimming" being longer than all other word types, this shifts the information for those columns, making the report look terrible. Additionally, it seems like the comma in the "Amount" Column is shifting the output as well.
fout << s.getID()
<< right << setw(11) << addCommas(s.getAmount()) << "\t"
<< left << setw(14) << s.getType() << "\t"
<< left << setw(14) << s.getLength() << "\t"
<< left << setw(10) << s.getDate() << " "
<< left << setw(15) << s.getFname() << "\t"
<< s.getLname() << endl;
lineCount++;
Current Program Output
(Currently messing with those setw values so please disregard that they don't line up with the header at the moment)
EDIT: Changed my font in VS to Helvetica because Consolas hurts my eyes, this also affected the output of my .dat, so essentially this was a non-issue. Yikes.
If you add std::internal to your std::cout statement, it'll pump the remaining spaces out, and you can do a new setw after that. This might work better than tabs for you, especially if you're not using a monospaced font. See an example in this answer. Make sure your setw is large enough to accommodate your largest words... and don't do using namespace std, it's poor practice. Shame on you! ;)
This question already has answers here:
How can I pad an int with leading zeros when using cout << operator? [duplicate]
(7 answers)
Closed 9 years ago.
Here's the code I'm trying to change
string binary = "000000100001000100010000000100000"
bitset<32> set(binary);
cout << hex << set.to_ulong() << endl;
The code shows 2112010 but I want it to show 02112010.
std::cout << std::setfill('0') << std::setw(5) << i << std::endl;
that is the same number you can format it with the 0 by using format specifiers if you need to retain the zero you need to store it as a string,
printf("%-8s - %s\n", c->name ? c->name : "", c->help);
I think what you're looking for is
cout << left << setw(8) << (c->name ? c->name : "") << " - " << c->help << endl;
The left and setw(8) manipulators together have the same effect as the %-8s formatting specifier in printf. You will need to #include <iomanip> in order for this to work, though, because of the use of setw.
EDIT: As Matthieu M. pointed out, the above will permanently change cout so that any padding operations print out left-aligned. Note that this isn't as bad as it might seem; it only applies when you explicitly use setw to set up some padding. You have a few options for how to deal with this. First, you could just enforce the discipline that before using setw, you always use either the left or right manipulators to left- or right-align the text, respectively. Alternatively, you can use the flags and setf function to capture the current state of the flags in cout:
ios_base::fmtflags currFlags = cout.flags();
cout << left << setw(8) << (c->name ? c->name : "") << " - " << c->help << endl;
cout.setf(currFlags, ios_base::adjustfield);
This works in three steps. The first line reads the current formatting flags from cout, including how it's currently aligning padded output. The second line actually prints out the value. Finally, the last line resets cout's output flags for internal alignment to their old value.
Personally, I think the first option is more attractive, but it's definitely good to know that the second one exists since it's technically more correct.
If you've got the Boost libraries:
std::cout << boost::format("%-8s - %s\n") % (c->name ? c->name : "") % c->help;