Ending char* vector in c -

how mark end of char* vector '\0' null-terminate it? if have char* vector:

 char* param[5]; 

i thought of either

 param[4] = '\0'; 

or

char c = '\0'; param[4] = &c; 

but none of them seem work?

param char-pointer vector, supposed point 5 strings(char-vectors).

ok trying end vector of strings, similar passed main argv. in case need assign null pointer:

param[4] = 0;