Thread: c program to decrement a large number with minimum execution time

I have tried to decrement a large integer value with less execution time, to achieve that i am declaring a variable with register keyword like register unsigned int value from this i have not received any optimization results while run this program with/without using this register keyword. please correct me if i am wrong. and please share if we have any other method to decrement a larger number with minimum execution time.
program mentioned here is just for example with register keyword(one of the optimization method to reduce execution time) main aim of this question is how to decrement a larger number with minimum execution time.

Code:

#include <stdio.h>
#include <time.h>
unsigned int decrement(unsigned int value);
main()
{
    clock_t start, end;
    double cpu_time_used;
    register unsigned int value;
    value = 4294967;
    start = clock();
    decrement(value);
    end = clock();
    cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;
    printf("cpu_time_used %lf\n",cpu_time_used);
}

unsigned int decrement(register unsigned int value)
{
    int i;
    for(;value;value--)
    {
        printf("loop value %u\n",value);
    }
    return 0;
}

It is quite likely that the bulk of the time is spent in output rather than in the decrement. I posit that chasing this micro-optimisation is barking up the wrong tree, and it is quite possible that the right optimisation is to simply write:

Code:

value = 0;