Szathmáry László honlapja @ DEIK

Center a text

In the terminal you want to center a text in a field of a given width.

In Python:

>>> s = "hello"
>>> s.center(20)
' hello '
>>> s.center(20, '.')
'.......hello........'
>>>

In C# I didn't find such a method so I wrote it as a custom extension. Here is how to use it:

csharp> var s = "hello"
csharp> s.Center(20)
" hello "
csharp> s.Center(20, '.')
".......hello........"
csharp>

Implementation:

// center a string in a field of given width (like Python's str.center())
public static string Center(this string s, int width, char fillChar=' ')
{
var leftMarginWidth = (width - s.Length) / 2;
if (leftMarginWidth < 0)
{
leftMarginWidth = 0;
}
var rightMarginWidth = width - s.Length - leftMarginWidth;
if (rightMarginWidth < 0)
{
rightMarginWidth = 0;
}
return string.Format("{0}{1}{2}", new string(fillChar, leftMarginWidth),
s,
new string(fillChar, rightMarginWidth));
}

Some tests:

[Fact]
public void Center()
{
Assert.Equal(" * ", "*".Center(10));
Assert.Equal("....*.....", "*".Center(10, '.'));
Assert.Equal("....**....", "**".Center(10, '.'));
Assert.Equal("...***....", "***".Center(10, '.'));
Assert.Equal("**********", "**********".Center(10, '.'));
Assert.Equal("***********", "***********".Center(10, '.'));
Assert.Equal(".hello..", "hello".Center(8, '.'));
}

See the current version here.

20180406a

Center a text