3 way comparison

gistfile1.c

//
//  main.c
//  optimize
//
//  Created by Rodrigo Basa on 2014-05-29.
//  Copyright (c) 2014 Rodrigo Basa. All rights reserved.
//

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>

double time_diff(struct timeval x , struct timeval y);

int main(int argc, const char * argv[]) {
    const int samples = 1000000;
    struct timeval start , end;
    double lessifs = 0;
    double orig = 0;
    double moreifs = 0;
    int w, x, f;
    char z;
    
    srand( (unsigned) time( NULL ) );
    
    for ( int i = 0; i < samples; i++ ) {
        // Common set of data
        w = rand() % 2;  // 0 or 1
        x = rand() % 80;  // 0 to 80
        f = rand() % 2;  // 0 or 1 converted to 'F' and 'M' below
        
        if ( f == 1 )
            z = 'M';
        else
            z = 'F';
        
        //Original
        gettimeofday(&start, NULL);
        if ( w == 1 ) {
            if ( z == 'M' ) {
                if ( x >= 20 && x <= 65 ) {
                    // statements 1
                } else if ( x < 20 ) {
                    // statements 3
                }
            } else {
                if ( x >= 20 ) {
                    if ( x <= 65 ) {
                        // statements 1
                        // statements 2
                    } else {
                        // statements 2
                    }
                }
            }
        } else {
            if ( z == 'M' ) {
                if ( x < 20 ) {
                    // statements 3
                }
            } else {
                if ( x >= 20 ) {
                    // statements 2
                }
            }
        }
        gettimeofday(&end, NULL );
        orig += time_diff( start, end );

        // Less ifs, no nesting
        // measure only the time spent in the conditional blocks
        gettimeofday(&start , NULL);
            if ( (w == 1) && (x >= 20) && (x <= 65) ) {
                // no statements to isolate execution time of the conditional and comparisons
            }
            
            if ( (x >= 20) && (z == 'F') ) {
                //
            }
            
            if ( (x < 20) && (z == 'M') ) {
                //
            }
        gettimeofday(&end , NULL);
        lessifs += time_diff( start, end );

        // More ifs, with nesting
        // measure only the time spent in the conditional blocks
        gettimeofday(&start , NULL);
            if ( x < 20 ) {
                if ( z == 'M' ) {
                    //
                }
            } else {
                if ( x <= 65 && w == 1 ) {
                    //
                }
                if ( z == 'F' ) {
                    //
                }
            }
        gettimeofday(&end, NULL);
        moreifs += time_diff( start, end );

    }
    printf( "Original               : %0.lf us\n", orig );
    printf( "Less ifs, no nesting   : %.0lf us\n" , lessifs );
    printf( "More ifs, with nesting : %.0lf us\n" , moreifs );

    return 0;
}

double time_diff(struct timeval x , struct timeval y)
{
    double x_ms , y_ms , diff;
    
    x_ms = (double)x.tv_sec*1000000 + (double)x.tv_usec;
    y_ms = (double)y.tv_sec*1000000 + (double)y.tv_usec;
    
    diff = (double)y_ms - (double)x_ms;
    
    return diff;
}