Question

I have the following code to assign a value to all the elements of a vector:

x = 100;

for (int i=0;i<vect.size();i++)
{
    vect[i] = x;
}

It’s straightforward enough, but I’m wondering if there is a function in the STL that does the same thing; something like for_each, but for assignment.

Answer 1

Use std::fill:

std::fill(vect.begin(), vect.end(), 100);

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Note if you want to initialize a vector to have all the same value, you can use the appropriate constructor:

std::vector<int> v(5, 100); // 5 elements set to 100

assign can be used to “reset the vector”, but if you’re just making the vector, use the constructor.