Size Of an Array

#1

Lets say i want to write a function that returns me the size of an array. some thing like

“”"

int calcNumberOfElements (int arr[]) {

int numberOfElements = sizeof(arr)/sizeof(int);

return numberOfElements;

}

“”"

since arrays are passed as a refernece , sizeof(arr) returns the size of int * rather than the array. So how can i modify this function to return me the number of elements in an array ?

#2

for character array
you can write like

while(arr[i]!=’\0’){
i++;
return i;

but for integer array there is no such method to find size of array inside function
that’s why every time we pass size of array along with array in functions

#3

seems like defining a macro works
#define NUMBER_OF_ELEMENTS(arr) (sizeof(arr) / sizeof(arr[0]))
and it works just fine when called as
int numberOfElements = NUMBER_OF_ELEMENTS(arr);
Can u please let me know , how it exactly works and also if it is a good practice to use such implementation ?

#4

this is not what you ask
you ask to find size of arr inside function which is not possible

#define NUMBER_OF_ELEMENTS(arr) (sizeof(arr) / sizeof(arr[0]))
this is macro
it will work simillar to function

you can right it in main also
int n=(sizeof(arr))/sizeof(arr[0]);

#5

sorry if my previous question wasn’t clear but my goal with extracting it out was to reuse the code and not have duplication incase i need it for some other array.
so the doubt i had is if macro also works as a function then why is it that inside the macro we can get sizeof(arr) while inside a function i can’t ?

#6

macro works like function but it is a not function\

it is defined globally so it access arr directly
function are removed form memory after completion of function but this is not for macros

#7

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