How to parse a token from a string in C?

Question

How to parse markers from the input string. For instance:

char *aString = "Hello world". 

I want the output to be:

"Hello World"

Answer 1

You want to use strtok - here is a good example.

Answer 2

Take a look at strtok , part of the standard library.

Answer 3

For repeat versions, you can use strtok_s for visual studio or strtok_r for unix

Answer 4

strtok is a simple answer, but you really need a lexer that does it right. Consider the following:

• Is there one or two spaces between hello and the world?
• can it be any number of spaces?
• can include vertical spaces (\ n, \ f, \ v) or just horizontal ones (\ s, \ t, \ r)?
• can include any space characters UNICODE?
• if there were punctuation between the words ("hello world"), would punctuation be a separate marker, a part of "hello" or ignored?

As you can see, writing the right lexer is not easy, and strtok not the right lexer.

Other solutions may be single-character end machines that do exactly what you need, or a regular expression solution that makes word searching easier than spaces. There are many ways.

And, of course, it all depends on your actual requirements, and I don’t know them, so start with strtok . But it’s good to know the various limitations.

Answer 5

Keep in mind that strtok is very hard to understand because:

• He changes the input
• The delimiter is replaced by a null terminator
• Combines adjacent delimiters and, of course,
• Not stream protected.

You can read about this alternative .