In C++ the sizeof operator is pretty handy. It is also useful to know the size of an array. The countof operator is useful for that, here’s how you define it:
#define countof(a) (sizeof(array) / sizeof(0[(array)]))
And an example of how it could be used:
SomeStruct myStruct[] = { {value1,value2} , {value1_1,value2_1} };
for (int i = 0; i < countof(myStruct); i++)
{
myStruct[i].TheValueA = SomeNewValue;
}