CODEWITHSUNDEEP
csplit
Devanshu Misra
Devanshu Misra

Reputation: 823

Splitting a string and using index to call the desired element

Splitting a string with a defined delimiter and then using indexes to call the element required is a pretty easy job in python. Specifically, calling the second last element from a list of variable length(since the string given can have a lot of elements after splitting), is a cakewalk because of the simple syntax.

Example:

str = "swscan.apple.com"
str_list = str.split(".")
print(str_list)
print(str_list[-2])

Output of this would be:

['swscan', 'apple', 'com']
apple

But doing the same thing in C is a pretty tedious job. I have to use strtok function for the same, which is further stored in a pointer value, and is then traversed through, which gives us the elements after splitting.

I am able to achieve this, but the thing that really puts me off is the part where I have to access the second last element of the same. Can somebody help me on how this can be achieved? Here is what I have done so far:

int main()
{
    char str[] = "swscan.apple.com";
    int init_size = strlen(str);
    char delim[] = ".";

    char *ptr = strtok(str, delim);

    while(ptr != NULL)
    {
        printf("'%s'\n", ptr);
        ptr = strtok(NULL, delim);
    }
    return 0;
}

The output of this would be:

'swscan'
'apple'
'com'

But this still does not come in a structured format with which I can access the second last element using the indexes. Any help would be appreciated. Thanks in advance.

Upvotes: 4

Views: 702

Answers (1)

Mohit Jain
Mohit Jain

Reputation: 30489

You can store the last two items in an array and print the second last item.

[...]
    char delim[] = ".";
    char *lastElement[2] = {0};  /* 1. To store delimited items */

    char *ptr = strtok(str, delim);

    while(ptr != NULL)
    {
        lastElement[0] = lastElement[1];  /* 2. Update */
        lastElement[1] = ptr;
        printf("'%s'\n", ptr);
        ptr = strtok(NULL, delim);
    }
    if(lastElement[0]) {  /* 3. Does second last item exist */
        printf("%s\n", lastElement[0]);  /* 4. Second last item */
    }
[...]

Check on ideone

This idea can be extended to get any arbitrary element also.

Upvotes: 2

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