The fastest way to create random vectors for benchmarking

Question

So, I just play around implementing some sorting algorithms in C ++, but I find it annoying to compare them at the moment because of how long it takes to not run the algorithm, but to create the input. I am currently testing each input length (1000, 2000, ...) 10 times to get some average time. For each of these 10 times, I create a new random of the vectorcorrect length by doing:

    // Each of the 10 times.
    for(int j = 0; j < 10; j++) {

        A.clear();

        // 'i' is the current input size.
        for(int k = 0; k < i; k++) {
            A.push_back(rand() % 10000);
        }

        // Other stuff
    }

Is there a better way to do this? Do I have to worry about closing rand () at 10,000, or is it just my brain OCD like round numbers? (That is, whether this modulo operation can really take a significant amount of time when you consider that it has been completed up to - at the moment - 10,000 for each out of 10 cycle). Alternatively, should I really create a new vector every time I run Sort? I did this because I felt that it was possible that the created vector could be biased, and therefore, if it was generated and then used 10 times, the answer could be completely disabled ...

Answer 1

Is there a better way to do this?

, , , . , std::vector, . , pre incrementing (++ var var ++) . , , , . , , , , unsigned short for.

, . , . , , , .

, , , , , . , , .

    A.reserve(i * i);
    for(unsigned short j = 0; j < 10; ++j) {            
        for(unsigned short k = 0; k < i; ++k) 
            A[k + (i*10)] = rand();                
        // Other stuff
    }

Edit

: 10 , unsigned char, . Win32, , .

    A.reserve(i * i);
    for(unsigned char j = 0; j < 10; ++j) {            
        for(unsigned char k = 0; k < i; ++k) 
            A[k + (i*10)] = rand();                
        // Other stuff
    }

Answer 2

cplusplus.com(http://www.cplusplus.com/reference/stl/vector/), :

" , , . , , , - vector::reserve."

vector::reserve .

EDIT: random_shuffle (http://www.cplusplus.com/reference/algorithm/random_shuffle/), (, random_shuffle ).

Answer 3

, :

#include <iostream>
#include <cstdlib>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sstream>

int main(int argc, char* argv[]){
    if (argc < 2){
        printf("No arguments found\n");
        exit(1);
    }
    int maxi;
    maxi = atoi(argv[1]);
    int * a;
    a = new int [5];

    std::stringstream ss;
    ss << maxi;
    printf(ss.str());
    printf("\n");
}