if else statements, loop - while, for and do while loop with many examples.
Array - 1D and 2D, why we need them and how to use them effectively.
String in C - NULL terminated character arrays.
Writing function, parameter passing to function. Returning value from function.
storage class - auto, static, extern and register
Pointer - in depth understanding.
Relationship between arrays and pointers.
Array of pointers.
Command line arguments
Reading and writing with files, both text and binary.
Recursion - how it works, recursion vs iteration in depth discussion - Towers of Hanoi
Various string utilities - sprintf, strtok and many others
bitwise operators in C programming.