What is a "code hero"?

In the works of Ernest Hemingway, a code hero is a man—and it's always a man—who lives by a certain moral code that provides him with some measure of certainty in an uncertain world. A code hero believes that when you're dead, you're dead, so death must be avoided at all costs.
That doesn't mean living a timid or unadventurous life; on the contrary, a code hero will face up to his own mortality by throwing himself into all manner of dangerous activities, be it war, big game hunting, or marlin fishing. A Hemingway hero must be afraid of death but not of dying. In the face of death, he must live his life more intensely. Only in this way will he be able to pass the test that life constantly sets, for the presence of death is a challenge to the code hero—an invitation to dig deep and discover his true being, to find out what he's really capable of.
As the code hero believes life to be inherently meaningless, little more than a great big nothing, he must shoulder the burden of creating meaning for himself, hence the need for a moral code by which he must live, and if necessary, die.

"Code Hero" stems from many of Ernest Hemingway's novels, in which the term is often used to describe the protagonist and his values. Typically, the protagonist operates under a "code" of his choosing which dictates his decisions and conduct. Usually, these ideals are courage, honor, and resilience in the face of immense pain, tragedy, or stress.
Hemingway builds violent worlds for his characters and submits those individuals to the whims of such chaos. His "heroes" are the characters who behave honorably while suffering and, thus, proves his masculinity and his value as a man. He looks his greatest fears—particularly death—squarely in the eyes. He is free-willed, an individualist, adventuresome, and closely guards and masks his personal feelings and emotions. Unfortunately, death frequently claims the Code Hero—the ultimate defeat. These qualities are closely related to our understanding of stoicism.
Hemingway's specific definition of the Code Hero is: "a man who lives correctly, following the ideals of honor, courage and endurance in world that is sometimes chaotic, often stressful, and always painful."