Thread: casting clock_t to unsigned long

I am looking at a piece of code from an exercise in the C Programming Language. It uses the clock_t data type for one of its variables. And then later when it prints the data of the variable, it does a cast to an unsigned long:

Code:

int main(void) {
    int testdata[MAX_ELEMENT];
    int index;                  /*  Index of found element in test data  */
    int n = -1;                 /*  Element to search for  */
    int i;
    clock_t time_taken;

    for ( i = 0; i < MAX_ELEMENT; ++i )
        testdata[i] = i;

 
    for ( i = 0, time_taken = clock(); i < 100000; ++i ) {
        index = binsearch(n, testdata, MAX_ELEMENT);
    }

    time_taken = clock() - time_taken;

    printf("binsearch() took %lu clocks (%lu seconds)\n",
           (unsigned long) time_taken,
           (unsigned long) time_taken / CLOCKS_PER_SEC);

Is there any particular reason to cast to unsigned long here rather than just using clock_t since that is what it was initialized to?

printf doesn't support format specifier for clock_t?