Thread: C Function to sort a string based on a delimiter

I Need to write a function using C wherein I should do the followingi) The function will receive a string in a character pointer(ii) This string will adhere to the following structure: "Kentucky+New York+Arizona+Nevada" The number of states can differ from 4 to 50 The delimiter between States can differ from '+' to ',', hence I would like to pass the delimiter to the function.(iii) This string should then be sorted alphabetically from left to right. The above example would then become: "Arizona+Kentucky+Nevada+New York"(iv) This string needs to be returned from the function using a character pointer.Please help me in this.

For starters, try to come up with an algorithm to solve the problem.

Originally Posted by mehimadri

I Need to write a function using C wherein I should do the followingi) The function will receive a string in a character pointer(ii) This string will adhere to the following structure: "Kentucky+New York+Arizona+Nevada" The number of states can differ from 4 to 50 The delimiter between States can differ from '+' to ',', hence I would like to pass the delimiter to the function.(iii) This string should then be sorted alphabetically from left to right. The above example would then become: "Arizona+Kentucky+Nevada+New York"(iv) This string needs to be returned from the function using a character pointer.Please help me in this.

You should probably use strtok in order to divide your string into substrings (see here a tutorial on how to use strtok properly).
Then, you will probably need to put them into a string array and use a sorting algorithm to arrange them in the correct order. After that you will need to iterate through your string array and concatenate them into another string. (see here some examples on how to copy, concatenate and compare strings).

I personally don't like strtok because it destroys the original string. You could copy it to another to keep the text intact, but that seems wasteful.

There are a number of string functions that will find a delimiter and/or set of characters and return an index or pointer to it.

strpbrk
strspn
strchr

These will return a pointer or index to the first found, but by creative use of pointers, you can feed subsequent calls with a char pointer to where you want the search to start.