C how does strtok work

The CCE accomplishes this by giving strtok a copy of the string and then freeing the copy. Whoops, the CS isn't actually freeing the copy A fully rigorous solution would do sophisticated data flow analysis on the pointed-to strings Even if the code does the right thing, it may still be considered a mistake and 'fixed' by a future maintainer, which can lead to vuls later on Ok, so it's not too strict too say that the only valid use for a string after getting passed to strtok is as an argument to strcpy , memcpy , free , or as the lhs to an assignment?

Because strcpy is safe in this instance, as the destination string 's memory is allocated to be large enough to hold it. Pages Boards. Page tree. Browse pages. A t tachments 0 Page History People who can view. Characters and Strings STR. Jira links. Extracting a single token The following piece of code will just split up the Hello world string in two and will return the first token extracted from the function.

Extracting all possible tokens To find all possible splits of the string, based on a given delimiter, the function needs to be called in a loop.

Keep Exploring. Related Courses. Learn in-demand tech skills in half the time. Early Access Courses. Assessments New. Free Trial New. The strtok function stores data in an internal static variable which is shared among all threads. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow.

Learn more. How does the strtok function in C work? Asked 7 years, 10 months ago. Active 7 years, 10 months ago. Viewed 28k times. Improve this question. And it doesn't make sense to anyone.. OT: It's int main void by the way. A function that is not required to be reentrant is not required to be thread-safe. In subsequent calls, s is a NULL pointer and lasts shall be unchanged from the previous call so that subsequent calls shall move through the string s , returning successive tokens until no tokens remain.

The separator string sep may be different from call to call. When no token remains in s , a NULL pointer shall be returned. Upon successful completion, strtok shall return a pointer to the first byte of a token.