Ch3.7: continue

The continue Statement

A continue statement skips the rest of the loop body and jumps directly to the next iteration.

continue;

It does not exit the loop. It only skips the remaining statements in the current iteration.

continue in a while Loop

This loop prints only even numbers.

::std::uint_least32_t i{};

while (i != 10) {
    if (i % 2 == 1) {
        ++i;
        continue;   // skip odd numbers
    }
    println("even: ", i);
    ++i;
}

continue in a for Loop

continue jumps directly to the loop’s step expression.

for (::std::uint_least32_t i{}; i != 10; ++i) {
    if (i % 3 != 0) {
        continue;   // skip non-multiples of 3
    }
    println("multiple of 3: ", i);
}

continue in Dead Loops

In a dead loop, continue simply restarts the loop.

::std::uint_least32_t i{};

for (;;) {
    ++i;
    if (i < 5) {
        continue;   // restart the loop
    }
    println("i reached 5");
    break;          // stop the loop
}

continue with Init-statement Loops

continue behaves normally even when the loop uses an init-statement.

for (auto i = 0; i < 10; ++i) {
    if (i == 4) {
        continue;
    }
    println("i=", i);
}

Nested Loops

continue affects only the innermost loop.

for (::std::uint_least32_t i{}; i != 3; ++i) {
    for (::std::uint_least32_t j{}; j != 3; ++j) {
        if (j == 1) {
            continue;   // skips only the inner loop's iteration
        }
        println("i=", i, ", j=", j);
    }
}

Pseudo-graph: Where continue Goes

          ┌───────────────┐
          │     loop       │
          │    begins      │
          └───────┬───────┘
                  │
                  ▼
          ┌───────────────┐
          │     cond       │─── false ───▶ loop ends
          └───────┬───────┘
                  │ true
                  ▼
          ┌───────────────┐
          │     body       │
          └───────┬───────┘
                  │
                  ├──▶ if (continue) ───────▶ step ─────▶ cond
                  │
                  ▼
          ┌───────────────┐
          │      step      │
          └───────┬───────┘
                  │
                  └─────────────── back to cond
      

Key takeaways

• continue skips the rest of the loop body: it does not exit the loop.
• continue jumps to the next iteration: in for, it jumps to the step expression.
• Nested loops: only the innermost loop is affected.
• Dead loops: continue simply restarts the loop.
• Clarity: use continue intentionally; avoid hiding it deep inside complex logic.