how to count number of strings being used in an array of strings

hi everyone, my title seems confusing but i didnt know how to word it any other way so ill explain it a bit better here.

i have declared an array of strings to be,dir[30][13]. Now my program is supposed load file names into those strings and i want to know how i can count the number of strings being used in that array of strings.

ive tried doing while(dir[i]!=NULL) and various other combinations of functions but i cant think of how to solve this problem.

In my program if i want to add a new file to the dir with user input and the dir is full (all string arrays are being used) then an error message of "directory is full" will show up.

your help is appreciated

Before operating on the array initialize every string in it with value of 0 using memset() function or for loop.
To count how many strings are entered use strlen() function or check if dir[i][0] != 0

Or count how many file names you process as you load them into the array and keep that number handy for later use. Start the count with 0 and each time you insert a file name into the array bump the count up by one.