CODEWITHSUNDEEP
c++exceptioncharstrtok
chapphw
chapphw

Reputation: 3

Exception: 'Access violation reading location'

Trying to read all words from a string with a strtok(), but it returns an exception when it reaches the end and I just can't figure out why. Sorry if duplicate.

strcpy(now, strtok(text, del));
do {
    if (palindrome(now))
        add_list(now);
    p = strtok(NULL, del);
    strcpy(now,p);
} while (p);

I get this:

Exception thrown at 0x7C07EE43 (ucrtbased.dll) in strings.exe: 0xC0000005: Access violation reading location 0x00000000.

Upvotes: 0

Views: 1780

Answers (1)

rustyx
rustyx

Reputation: 85361

I see 2 issues with the code:

  1. The first call to strtok can return NULL. If that happens, you should not call strtok again.

  2. The second call to strtok can return NULL. In that case strcpy(now,p); will crash, since it's arguments may not be NULL.

Change the code to something like this (untested):

p = strtok(text, del);
while (p) {
    strcpy(now, p);
    if (palindrome(now))
        add_list(now);
    p = strtok(NULL, del);
}

Upvotes: 2

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