I'm working on the check() part of dictionary.c. I wanted to use strcasecmp() to compare the text word and the word in my dictionary. Nevertheless, it doesn't work. It keeps pop up the error :

dictionary.c:115:19: error: implicit declaration of function 'strcasecmp' is invalid in C99 [-Werror,-Wimplicit-function-declaration] result = strcasecmp(cursor,word);

Then, I used the sandbox to test code with strcasecmp(), and there is a weird bug.

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I believe these two codes are 100% identical, but the one with the comment is able to compile, while the one without comment can't compile. And it's the same error with the code in my dictionary.c

1 Answer 1



   #include <strings.h>

Note the "s" on the end. string.h and strings.h are two different libraries. Try including both.

Haven't checked, but my next question is whether there are conflicting functions with the same name in both. and my answer is that there wouldn't be conflicting functions because these are well written and widely published standard libraries. If there were any conflicts, they would have been fixed long ago.

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