Arrays in C

From the C cheat sheet · Arrays · verified Jul 2026

Declaration, iteration, and the pointer relationship.

// Quick Reference
int a[5] = {1, 2, 3};   // rest are 0
int n = sizeof(a) / sizeof(a[0]);   // length
int grid[2][3];         // 2D

💡 sizeof(a)/sizeof(a[0]) gives the length - but only before the array decays to a pointer.

⚡ Passing an array to a function passes a pointer; send the length as a separate argument.

📌 C does no bounds checking - writing past the end is undefined behavior (buffer overflow).

🟢 { 0 } zero-initializes the whole array; partial initializers fill the rest with 0.

arrays