What's "<?=" operator in C++?

I came across the following code here, which is from the C++ implementation of Dijkstra algorithm using an adjacency matrix.

//read in edges keeping only the minimum
for(int i=0; i<E; i++) {
    int v1,v2,tmp;
    fin >> v1; fin >> v2;
    fin >> tmp;
    adjmat[v1][v2]<?=tmp; // <?= sets left to min(left,right)
    adjmat[v2][v1]<?=tmp;
}

Pay attention to the last two lines, which apply operator <?=. As being commented, the following line

adjmat[v1][v2]<?=tmp; // <?= sets left to min(left,right)

will set left to min(left,right).

I never see this operator before. I tried the code in VS, it can not compile. What is it? How can it set left to be min(left,right)?

What's "<?=" operator in C++?

2 Answers