Warning messages compiling C program

When compiling a C program i get the following warnings.How do i modify the code to remove these warning messages?

1) "test.c", line 614: warning #4212-D: mismatch between character pointer
types "unsigned char *" and "char *"
p_data = m_lines[p_text_idx];

p_data is defined as char *p_data_text = NULL;
m_lines is defined as static unsigned char **m_lines;


2) "test.c", line 919: warning #2513-D: a value of type "int" cannot be
assigned to an entity of type "char *"
if ((cp = strrchr(p_file_path, '/')) == NULL)
^

where char *cp = NULL;
and char p_file_path[MAXPATHLEN];


3) "test.c", line 1033: warning #4212-D: mismatch between character pointer
types "unsigned char *" and "char *"
p_result = m_nls_lines[p_nls_idx] + p_len;

where char *p_result = not_found; and static unsigned char **m_nls_lines = NULL;

Thanks,
Puth