Generating a 12Digit Alphanumeric password 2

Karl Blessing · Mar 8, 2000

I need something that'll create a quick alphanumeric(a->z, A->Z, 1->0) 12 digit character array 
something i can just throw in a char something[13]; Karl <a href=mailto:kb244@bellsouth.net>kb244@bellsouth.net</a> <a href=

http://kb244.8m.com>

</a>

Karl Blessing · Mar 9, 2000

Ok i looked into it, got something made, tho microsoft MSDN was no help at all, and i do remeber there used to be a random command where you just stick in the ranges, but M$ had no info on this instead i came up with this lil example 
 
#include <iostream.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <time.h> 
 
void main( void ) 
{ 
int i,j; char tmp[13]; 
i=j=0; 
srand( (unsigned)time( NULL ) ); 
for( i = 0; i <= 12;i++ ) 
{ 
 
while((j<48) ¦¦ ((j>57)&&(j<65)) ¦¦ ((j>90)&&(j<97)) ¦¦ (j>122)) 
{ 
j = rand(); 
} 
tmp = j; 
cout<<j<<' '; 
j=0; 
} 
tmp[13]='\0'; 
cout<<'\n'<<tmp; 
} 
/* 
48->57 numbers 
65->90 capital letters 
97->122 lowercase letters 
*/ 
Karl <a href=mailto:kb244@bellsouth.net>kb244@bellsouth.net</a> <a href=

http://kb244.8m.com>

</a>

francisco · Jul 7, 2000

Hello karl, i couldn´t compile your source code with my Microsoft VC++  compile, I had to make some changes, first of all remember that an n element array in C are numerated from 0 to n-1, and you have to asign  a value to each element of this array, here comes my codes with some comments. It was beautiful to see your program. #include <iostream.h> #include <stdlib.h> #include <stdio.h> #include <time.h> #include <string.h> void main( void ) { int i,j,nCount; char tmp[13]; i=j=0; srand( (unsigned)time( NULL ) ); for( i = 0; i < 12;i++ ) { while((j<48) ¦¦ ((j>57)&&(j<65)) ¦¦ ((j>90)&&(j<97)) ¦¦ (j>122)) { j = rand(); } tmp =   j;                               //You have to asign each character individually cout<<j<<' '; j=0; } tmp [12]='\0';                          //The last element of your string is tmp [12] nCount=strlen(tmp);              //with it I count the lenght of the string cout<<'\n'<<tmp<<'\n'; cout <<"Lenght of the string is "<< nCount<<'\n'; } /* 48->57 numbers 65->90 capital letters 97->122 lowercase letters */ Javi

palbano · Jul 7, 2000

Karl, To generate a number between 48 and 122 do this: int num = (rand() % (122 + 48)) + 48; You will still have to check for the gaps Good luck -pete

Karl Blessing · Jul 7, 2000

this is an extremly old topic I forgot about, and Javi I know its zero-based(your implementation is nice too), and palbano, I appreciate that implementation(the project is long old that used that), it will at least help others if they need an random alphanumeric generator. Karl <a href=mailto:kb244@kb244.8m.com>kb244@kb244.8m.com</a> <a href=

http://kb244.8m.com>

</a> Experienced in : C++(both VC++ and Borland),VB1(dos) thru VB6, Delphi 3 pro, HTML, Visual InterDev 6(ASP(WebProgramming/Vbscript)

http://www.brainbench.com/transcript.jsp?pid=629151

WilMead · Jul 10, 2000

Here's some odd tid bits Alpha      are 0x40 for 26               and 0x60 for 26 Numerics are 0x30 for 10 Notice Alpha case shifts by exclusive ORing a hex 20 (0x20) Using this information int d(int x) { // return random number between 0 and x-1   return (rand() % ((2>x), 2, x));  // Don't let bad input screw things } char c() { // Return random alphanumeric    if (d(2)) return (0x30 + d(10));              // Numeric this time.    return (0x40 + d(26) + (d(2) * 0x20));   // Numeric fell thru go alpha. } This allows : for( i =0; i < (sizeof(pwd)-1); i++)   pwd[ i ]  = c(); One could eliminate the d(x) function at the cost of code readability.   Even with that, the maintainability of this solution is outweighed by the performance hit.   A solution that addresses both performance and maintenance uses an array of char containing all your valid characters in a random sequence and a random index to pick a character to return. char c() { char csMyChars[] = "thelist of chars..."; return csMychars[rand() % (sizeof(csMyChars)-1)]; } // or something like that. Again allowing main stream code such as : for( i =0; i < (sizeof(pwd)-1); i++)   pwd[ i ]  = c(); This reduces your overhead dramatically as it eliminates the multiple random number generator calls and virtually eliminates the need for any logic at all.  The offsetting cost is a little space in the data section and a visible literal in your executable.  It does have the added benifit of allowing you to tune your base set and give more or less weight to certain outcomes.  If you want to give numerics a higher probability of inclusion, simply increase their presence in the base array.  Likewise if you want to totally eliminate the possibility of a value, simply don't include it in the base set. Since I hate involved logic when other simpler methods exist I prefer the last solution.  Besides providing the most versitility, it is the fastest executing and easiest to maintain version.  Still, nothing I've seen so far is off your path.   In the words of a very wise person: "Less is more." Hope this helps, Wil Mead <a href=mailto:wmead@optonline.net>wmead@optonline.net</a> <a href= > </a>

WilMead · Jul 10, 2000

Pete, Perhaps int num = (rand() % (122 - 48)+1) + 48; would work much better. Algorithm:    generate random number 0 to size-of-range -1, or modulo size-of-range.    Add Base offset to generated number.    size-of-range = (max - min) +1 Another example, generate random between 4 and 5  (5-4) + 1 is 2  rand() % 2 is 0 or 1  Add that to 4 yielding 4 or 5. Wil Mead <a href=mailto:wmead@optonline.net>wmead@optonline.net</a> <a href= > </a>

WilMead · Jul 10, 2000

Oops -- fudged the alpha start points... They are 0x61 and 0x41. Wil Mead <a href=mailto:wmead@optonline.net>wmead@optonline.net</a> <a href= > </a>

palbano · Jul 10, 2000

Wil, I'm sure you are correct. I don't concern myself with 'off by one' math errors in example code. That is left to the developer as a final task. But I appreciate your thoroughness... is that a word? ;o) -pete

WilMead · Jul 10, 2000

Actually that was only to draw your attention to the mis-coded triadic. return (rand() % ((2>x), 2, x)); should be return (rand() % ((2>x) ? 2 : x)); Wil Mead <a href=mailto:wmead@optonline.net>wmead@optonline.net</a> <a href= > </a>

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Generating a 12Digit Alphanumeric password 2

Karl Blessing

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Karl Blessing

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WilMead

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WilMead

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palbano

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