Multiply vector elements by a scalar value using STL

Question

Hi I want to (multiply,add,etc) vector by scalar value for example myv1 * 3 , I know I can do a function with a forloop , but is there a way of doing this using

Answer 1

I know this not STL as you want, but it is something you can adapt as different needs arise.

Below is a template you can use to calculate; 'func' would be the function you want to do: multiply, add, and so on; 'parm' is the second parameter to the 'func'. You can easily extend this to take different func's with more parms of varied types.

template
_ITStart xform(_ITStart its, _ITEnd ite, _Func func, _Value parm)
{
    while (its != ite) { *its = func(*its, parm); its++; }
    return its;
}
...

int mul(int a, int b) { return a*b; }

vector< int > v;

xform(v.begin(), v.end(), mul, 3); /* will multiply each element of v by 3 */

Also, this is not a 'safe' function, you must do type/value-checking etc. before you use it.