Why does the for loop use a semicolon?

Question

In most C-derived languages (C, Java, Javascript, etc), the for loop is of the same basic syntax

for (int i = 0; i < 100; i++) {
    // code here
}

Why does this syntax contain semicolons, when semicolons are usually reserved for the end of the line? Also, why is there no semicolon after i++?

Answer 1

This pseudo-code:

for (A; B; C) {
    D;
}

can be internally converted to

{ // scope bracket
    A;
    while (B) {
        D;
        C;
    }
}