[RESOLVED] Clarification required: char* and null terminators

[wossname]

I need a function to add an ordinal suffix to an integer. ie. ordinalize(...1) gives "1st", ordinalize(...2) gives "2nd" and so on.

I'm porting some C# code that already does this but i'm uncertain about how to handle the null terminators on the end of the string...

void ordinalize(char *buf, int n);
{
    char *ends[10] = {"th","st","nd","rd","th","th","th","th","th","th"};
    int t = (n < 0 ? -n : n) % 100;
    t %= ((t >= 11 && t <= 13) ? 1 : 10); //anything modded by 1 is always 0, this forcing a "th" out of the ends array...

    sprintf(buf, "%d%s", n, ends[t]);
}

(fills the buf array with the string we require)

I'm calling this with:

char *temp[13]; //number will need 10 digits max plus 2 chars plus the null terminator
ordinalize(temp, 12345);
//temp now equals????

My questions:
1) Is a char array's contents always zeroes when its declared or is it undefined?
2) Does sprintf add a null terminator?
3) Do I need to manually add any null terminators anywhere?