对齐ofstream的输出

Question

I wish to output data from my program to a text file. Here is a working example showing how I do it currently, where I also include the date/time (I am running Windows):

#include <iostream>
#include <fstream>
#include <time.h>

using namespace std;

int main()
{

char dateStr [9];
char timeStr [9];

_strdate(dateStr);
_strtime(timeStr);

ofstream output("info.txt", ios::out);
output << "Start time part 1 " << "\t" << timeStr << " on " << dateStr << "\n";
output << "Start time part 1000000 " << "\t" << timeStr << " on " << dateStr << "\n";
output.close();


return 0;
}

However the output of "info.txt" is not very readable to me as a user, since the time- and date stamp at the ends are not aligned. Here is the output:

Start time part 1   15:55:43 on 10/23/12
Start time part 1000000     15:55:43 on 10/23/12

My question is, is there a way to align the latter part?

Answer 1

是的,<iomanip>header提供了setw操纵器,允许您设置输出的每个字段的宽度ostream.setw对每行使用操纵器而不是制表符可以更好地控制输出:

output << setw(25) << "Start time part 1 " << timeStr << " on " << dateStr << endl;
output << setw(25) << "Start time part 1000000 " << timeStr << " on " << dateStr << endl;

要对齐左侧的字符串,请添加left操纵器:

output << left << setw(25) << "Start time part 1 " << timeStr << " on " << dateStr << endl;
output << left << setw(25) << "Start time part 1000000 " << timeStr << " on " << dateStr << endl;