• For sure it’s premature optimization, thus performance arguments are omitted.
• Thus it’s a question of style.
  • memset
    • ensures whole struct is zeroed, however hides initialization of individual members (though they are usually meant to be initially zero)
  • memberwise
    • explicitly indicates what we are doing with the structure
    • prone to leaving out some members -> hard to hunt non-deterministic bugs
    • not robust against ABI changes
  • conclusion:
    • Prefer memset.
    • Use calloc.