What's the best way to reset a char[] in C?

Question

I use a string:

char    word[100];

I add some chars to each position starting at 0. But then I need be able to clear all those positions so that I can start add new characters starting at 0.

If I don't do that then if the second string is shorten then the first one I end up having extra characters from the first string when adding the second one since I don't overwrite them.

Answer 1

If you want to zero out the whole array, you can:

memset(word, 0, sizeof(word));

Answer 2

You don't need to clear them if you are using C-style zero-terminated strings. You only need to set the element after the final character in the string to NUL ('\0').

For example,

char buffer[30] = { 'H', 'i', ' ', 'T', 'h', 'e', 'r', 'e', 0 };
// or, similarly:
// char buffer[30] = "Hi There";  // either example will work here.

printf("%s", buffer);
buffer[2] = '\0';
printf("%s", buffer)

will output

Hi There
Hi

even though it is still true that buffer[3] == 'T'.