the algorithm used in c++ to generate random numbers

Hi,
could you please give me a hint about the algorithm that c++ uses when we use rand () command.
there are many algorithm. but most simple one is:Linear Congruential Generator(LCG)

does c++ use (LCG) when we use rand () ??

thanks for your help

I don't think the standard defines rand()'s algorithm.

But have a look here(C++11):
Pseudo-random number generation - Cppreference

Why not find it out yourself?

Write a program that uses rand() and step into it with a debugger.

My compiler uses:

Code:

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return( ((ptd->_holdrand = ptd->_holdrand * 214013L + 2531011L) >> 16) & 0x7fff );

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Yours might differ.

The standard does not mandate what algorithm is used to implement functions, but rather its requirements, what input it must take and what it must return. It is up to the compiler vendor to implement that.

thanks for your help

Quote:

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Originally Posted by Elysia

The standard does not mandate what algorithm is used to implement functions, but rather its requirements, what input it must take and what it must return. It is up to the compiler vendor to implement that.

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Requirements are about more than inputs and outputs. Some requirements are about performance (or, more accurately, algorithmic complexity and space complexity).

That is what I meant by requirements. You just stated it a little more detailed.

I think srand is what you looking for... check cplusplus reference