If the text is being displayed or printed with a normal "kerned" font, then all punctuation should be followed by a single space. Double spacing should only be used for monospaced fonts (eg Courier), but even then only for sentence-ending punctuation like question marks, exclamation points and full stops (periods). This convention dates back to the days of the typewriter, which used monospace fonts.
Once.
One space after a semicolon.
Only one space follows a semicolon.
I am a genius! i know how many times Julie Payette went to space. Julie went into space 3 times.
3 times
Once.
When using a semicolon you put one space after the semicolon.
One space after a semicolon.
There should be one space.
Only one space follows a semicolon.
It makes a space in HTML coding.
4
After a semicolon, there is never more than one space. Spacing after colons (and periods) depends on the style guidelines you're using. Some call for one space, others for two. The most important thing, however, is to be consistent. Use the same spacing after colons as you do after periods throughout the entire document.
how many times has tom peake been to Space
I am a genius! i know how many times Julie Payette went to space. Julie went into space 3 times.
He has been in space 4 times
For clasesses it defines from which class to inherit. :: means area of visibility in certain name space.