Maman 12 Q3 in C

#include <stdio.h>

// slowest
int dCount1(unsigned int t1) {
    int t2=0;
    do {
        ++t2;
    } while ( ( t1 = t1 / 10 ) != 0 ) ;
    return t2;
}

// better since mul is faster than integer divide
int dCount2 (unsigned int t1) {
    int t2 = 0, t3 = 1;

    while ( t3 <= t1 ) {
        ++t2;
        t3 *= 10;
    }
    return t2;
}

// best since array will be in L1 cache after first use so we just have an
// increment and comparison.
int dCount3(unsigned int t1) {
    unsigned int sizes[] = { 0, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 };

    int t2 = 10;

    while ( t1 < sizes[t2] ) t2--;

    return t2;
}

int main(void) {
    unsigned int t1;
    char *str = "%d digits\n";

    while( scanf("%u", &t1) != EOF && t1 != 0 ) {
        printf(str, dCount1(t1));
        printf(str, dCount2(t1));
        printf(str, dCount3(t1));
    }
    return 0;
}