C sizeof Keyword
Example
Measure the memory size of different variables and types:
int myInt;
float myFloat;
double myDouble;
char myChar;
printf("%lu\n", sizeof(myInt));
printf("%lu\n", sizeof(myFloat));
printf("%lu\n", sizeof(myDouble));
printf("%lu\n", sizeof(myChar));
Try
it Yourself »
Definition and Usage
The sizeof keyword is an operator which measures the amount of memory used
by a variable or data type.
When a data type is specified it indicates how many bytes are needed to store data of that type.
When a variable is specified it indicates how many bytes of memory the variable occupies.
More Examples
Example
To count the elements in an array, divide the size of the array by the size of each element in the array:
int myNumbers[] = {10, 25, 50, 75, 100};
int length = sizeof(myNumbers) /
sizeof(myNumbers[0]);
printf("%d", length);
Try
it Yourself »
Related Pages
Read more about memory size in our C Memory Size Tutorial.
Read more about array size in our C Array Size Tutorial.