Known the password length generates an exhaustive dictionary.

Brute force.c

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

// number of characters into charset
#define CHARACTERS 62

// charset
static const char charset[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789"
//"\£$%&/()=!?^*-+,.-òàùè+;:_çé*@#][<>{|}"
;

int main(){
    int n=CHARACTERS;
    int k, i=0, j, new_line=0, EXIT;
    int index[k];
    
    FILE *fp;
    fp = fopen("Passwd.txt","w");
    if(fp == NULL){
        perror("\nError");
        exit(1);
    }
    
    printf("\nEnter the password length: ");
    scanf("%d",&k);
    
    memset(index,0,k * sizeof(int));
    
    while(1){
        EXIT = 1;
        
        for(i=0; i<k; i++){
            fprintf(fp,"%c",charset[index[i]]);
            if(index[i] < n-1)
                EXIT = 0;
        }
        
        fprintf(fp,"%c",'\n');
        
        if(EXIT){
            break;
        }
        
        ++index[k-1];
        
        for(j=k-1; j>=1; j--){
            if(index[j] >= n){
                index[j] = 0;
                ++index[j-1];
            }
        }
    }
    
    printf("End.\n");
    
    fflush(fp);
    fclose(fp);
    
    return 0;
}
    memset(index,0,k * sizeof(int));
    
    while(1){
        exit = 1;
        
        for(i=0; i<k; i++){
            fprintf(fp,"%c",charset[index[i]]);
            if(index[i] < n-1)
                exit = 0;
        }
        
        fprintf(fp,"%c",'\n');
        
        if(exit){
            break;
        }
        
        ++index[k-1];
        
        for(j=k-1; j>=1; j--){
            if(index[j] >= n){
                index[j] = 0;
                ++index[j-1];
            }
        }
    }
    
    printf("\nEnd.\n");
    
    fflush(fp);
    fclose(fp);
    
    return 0;
}