Random numbers

[Amit Sebiz]

hi!
I am using the following code to generate a random string. But each time i get the same string output. Can anyone help.

char myarray[22];
char* CGeneratorApp::GenerateString()
{
myarray[21]='\0';
for(int k=0;k<21;k++)
{
myarray[k] = (char)(((int)rand()%25)+65);
}

char first[2];
intUsed++;

sprintf(first,"%d",intUsed);

if(intUsed<10)
{
first[1]=first[0];
first[0]='0';
}

first[0]=(char)((int)first[0]+27);
first[1]=(char)((int)first[1]+27);

myarray[8]=first[0];
myarray[10]=first[1];

AfxMessageBox(myarray);

return myarray;
}

Thnx in advance

[Kheun]

You need to initialize the random seed using srand() before calling rand(). e.g. srand(clock());

[dude_1967]

Here is a related post which offers additional, useful information.

Sincerely, Chris.



http://www.codeguru.com/forum/showth...hreadid=281630

[Amit Sebiz]

Thnx Everybody,
U were of quite good help.

[yiannakop]

Originally posted by Kheun
You need to initialize the random seed using srand() before calling rand(). e.g. srand(clock());

Indeed, you need to call srand(), but not using clock(), because clock() will (possibly) return the same number, so the random seed will be initialized in the same way. A better way is to call srand like this:

srand( (unsigned)time( NULL ) );

[dude_1967]

Indeed,

Some developers even seed rand using some sort of a high-frequency ticker in the system, for example the time-stamp-counter in Pentium systems.

I think that this is described in some other posts such as the link in my other response above.

Sincerely, Chris.