warning : implicit declaration of function ' crypt_r'

Question

I am trying to write a multi-threaded program in which I need to call the function crypt. But the compiler throws this warning. Also it doesn't recognize crypt_data as well. Any ideas?

Answer 1

You need to include appropriate header file. In this case crypt.h

 #include <crypt.h>

Answer 2

声明函数crypt的原型（转发声明）或包括具有该原型的标头。

Answer 3

Pre-process the source of your program, eg by running gcc -E in place of gcc -c . Look at the output to see if some/all/none of the crypt functions you expect are appearing in the declarations.