How to add random numbers

[namcintosh]

I am trying to do a math tutor program which generates two random numbers from 1 to 50 and add them up. I have no clue as to where to start.

Any input is appreciated.

[JosAH]

Have a look at the rand() and srand() functions; both are declared in stdlib.h.
Read all about them here .

kind regards,

Jos

[namcintosh]

Have a look at the rand() and srand() functions; both are declared in stdlib.h.
Read all about them here .

kind regards,

Jos

Okay, thanks. I will let you have the honor of seeing my program when it is completed. :-)

[namcintosh]

Have a look at the rand() and srand() functions; both are declared in stdlib.h.
Read all about them here .

kind regards,

Jos

Well, I tried, and this is what happened:

Program
#include <iostream>
#include <cstdlib>
#include <conio>
using namespace std;

int main()
{
unsigned seed;
int num;

num = 1 + rand() %500;

srand (seed);

cout << rand() <<endl;
cout << rand() <<endl;
cout << rand() <<endl;

getch();
return 0;
}

Output:
130
10982
1090
Each time I run this program, I get the same three random numbers. what's the deal

[ilikepython]

Well, I tried, and this is what happened:

Program
#include <iostream>
#include <cstdlib>
#include <conio>
using namespace std;

int main()
{
unsigned seed;
int num;

num = 1 + rand() %500;

srand (seed);

cout << rand() <<endl;
cout << rand() <<endl;
cout << rand() <<endl;

getch();
return 0;
}

Output:
130
10982
1090
Each time I run this program, I get the same three random numbers. what's the deal

I think it is because you didn't set seed to anything. It is usually a good idea to set seed to the system time so it is different everytime you run the program.

srand(unsigned time(0))

also i think you have to include a time header file.

[namcintosh]

I think it is because you didn't set seed to anything. It is usually a good idea to set seed to the system time so it is different everytime you run the program.

srand(unsigned time(0))

also i think you have to include a time header file.

Okay, so this is the program
#include <iostream>
#include <cstdlib>
#include <time>
#include <conio>
using namespace std;

int main()
{
unsigned seed, time;
int num;

num = 1 + rand() %500; When I use this line, I get an error that says num is assigned to a value that is never used.

srand (seed);
srand (time);
cout << rand() <<endl;
cout << rand() <<endl;

getch();
return 0;
}

And this is my output:
10673
25698

See the problem?? it's not generating the two random numbers from the range of 1-500. When I ran it again, it got the same random numbers. What to do??

[JosAH]

You never use the value of 'num' anywhere in your code hence the warning.
For the identical output for each run: carefully reread the previous person's
reply again: the code uses a *function* time(), not a *variable* that is accidentally
named 'time'.

kind regards,

Jos

[namcintosh]

You never use the value of 'num' anywhere in your code hence the warning.
For the identical output for each run: carefully reread the previous person's
reply again: the code uses a *function* time(), not a *variable* that is accidentally
named 'time'.

kind regards,

Jos

Well, I tried that, and this is what happened:

#include <iostream>
#include <cstdlib>
#include <time>
#include <conio>
using namespace std;

int main()
{
unsigned seed, time;

time = 1 + rand() %500;

srand (seed);
srand (time);
cout << rand() <<endl;
cout << rand() <<endl;

getch();
return 0;
}

Output Line
4862
12702
Each time I run this, I get the same numbers. I don't want that. I want a different set of random numbers each time, in between the range of 1 to 500.

[weaknessforcats]

This always produces the same value:

time = 1 + rand() %500;

When uses with srand(), it's the same seed so you get the same numbers from rand().

Why not key in the seed???

[JosAH]

Each time I run this, I get the same numbers. I don't want that. I want a different set of random numbers each time, in between the range of 1 to 500.

You didn't read ilikepython's reply carefully enough. There is no need for a
local variable named time. It's the time() function that does it:

srand(time(0));

That seeds the random number generator to different values each time you run
your program because the value returned by the time() function will be different
each run.

kind regards,

Jos

[Ganon11]

You also have to put the srand() call before you generate any random numbers.

[namcintosh]

This always produces the same value:

time = 1 + rand() %500;

When uses with srand(), it's the same seed so you get the same numbers from rand().

Why not key in the seed???

So how do I get the random number that output on my screen to range from 1 to 500??? That is what I'm really trying to do.

[JosAH]

So how do I get the random number that output on my screen to range from 1 to 500??? That is what I'm really trying to do.

The following is statistically a bit incorrect, but for starters you could do:

int result= 1+rand()%500;

The variable 'result' will have a value in the interval [1, 500].

kind regards,

Jos

[namcintosh]

You also have to put the srand() call before you generate any random numbers.

Is this how I declare my range to be from 1 to 50??

srand(time(1+ra nd() % 50));

What is the zero for in the parenthesis???

[namcintosh]

The following is statistically a bit incorrect, but for starters you could do:

int result= 1+rand()%500;

The variable 'result' will have a value in the interval [1, 500].

kind regards,

Jos

So do I type the variable int result after the unsigned seed??