implicit declaration of function?

Code:

warning: implicit declaration of function `malloc'
warning: implicit declaration of function `strlen'
warning: implicit declaration of function `strcpy'

I am getting these messages when I compile my files with: gcc -Wall -ansi -pedantic -O *.c.
But if I compile with just gcc *.c the program compiles fine and works fine.

the lines that cause the message are:

Code:

p=(char*)malloc(strlen(buffer)+1);
strcpy(p,buffer);

Could you tell me what is wrong and what is the right way to do it? Thanks in advance.

You need to include the appropriate headers. In this case, stdlib.h and string.h

Thanks a lot, it is a simple thing but when you don't have much experience, it is a complex problem. I was trying to figure out for hours. I appreciate it, it compiles fine now.