help with password list generator

I'm trying to do a password list. I wan to be able to save in a file all possibles combination up to a determine length. The list should start with 0,1,3.....a,b,c.....0a,0b,0c, etc. all I have been able to do is do the list with only all possible combinations for the determine length only example if length is 3 the list starts with 001,002,003.... instead of 0,1,2.....001,002,003,etc. Can somebody help with this I'm stuck and out of ideas. Thanks a lot!!!
This my code so far

Code:

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void printAllPossiblePasswords(int length, const char* charset){
    char* str;
    const char** counters;
    int i;
    FILE *password;

        password=fopen("passwords.txt", "w+");
    str = malloc(length+1);
    counters = malloc(sizeof(char*)*(length + 1));
    counters[length] = 0;
    str[length] = 0;
    for (i = 0; i < length; i++)
    {
        counters[i] = charset;
    }

    while(1)
    {
        for (i = 0; i < length; i++)
            str[i] = *(counters[i]);

        fprintf(password,"%s\n", str);

        counters[0]++;
        for (i = 0; (i < length) && (*(counters[i]) == 0); i++)
        {
            counters[i] = charset;
            counters[i+1]++;
        }

        if (i == length)
            break;
    }

    free(str);
    free(counters);
    fclose(password);
}

int main ()
{

    int length;

    system("clear");
    printf("****************Password Hash Generator****************\n");
        printf("Enter the length of the password:");
        scanf("%d",&length);
        printf("Generating list...\n\n");
    printAllPossiblePasswords(length, "1234567890qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM[]-=;'\\,./!@#$%^&*()_+{}:\"|<>?~`");
    //printAllPossiblePasswords(length, "1234567890qwertyuiopasdfghjklzxcvbnm");

    FILE *hash;
    hash = popen("openssl passwd -salt -crypt -in \"passwords.txt\" > \"hashes.txt\"", "r");
    pclose(hash);

    printf("With great powers  come great responsabilities!");

    return 1;
}

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Code:

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for (int length = 1; length <= length_you_need; ++length) {
    run_your_program(length);
}

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First, I'd decide whether you want all possible combinations, or all possible *permutations*, and whether lowercase and uppercase letters will be treated as the same letter (case insensitive), or not.

Then, someone can help you out.

Is case sensitive and all possible combination. Example if length is 3 it should start with 0,1,2... all the up to ))) or zzz however you want to see it.

Probably not the most efficient, but one way is to use recursion

Code:

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std::vector<std::string> all_combinations(int length);

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For length = 1, just use a loop.

For length > 1, use a loop + all_combinations(length - 1)

*edit*
oops, C forum.

Basically, you need to return a list of strings (possibly as a parameter).
*/edit*