sizeof Operators in C Programming

In C, the sizeof operator is used to determine the size, in bytes, of a data type or a variable. It's often used in conjunction with arrays, structs, and other data types to calculate the memory space they occupy.

The syntax for the sizeof operator is:

sizeof(type);

sizeof(expression);

where type is a data type, and expression is any valid C expression.

Here are a few examples of how sizeof can be used:

• To determine the size of a data type:

  #include <stdio.h>
  
  int main() {
      printf("Size of int: %zu bytes\n", sizeof(int));
      printf("Size of float: %zu bytes\n", sizeof(float));
      printf("Size of char: %zu bytes\n", sizeof(char));
      return 0;
  }
  

  Output:

  Size of int: 4 bytes
  Size of float: 4 bytes
  Size of char: 1 bytes
  

• To determine the size of a variable:

  #include <stdio.h>
  
  int main() {
      int arr[10];
      printf("Size of the array: %zu bytes\n", sizeof(arr));
      return 0;
  }
  

  Output:

  Size of the array: 40 bytes
  

• To determine the size of a struct:

  #include <stdio.h>
  
  struct Person {
      char name[20];
      int age;
  };
  
  int main() {
      printf("Size of struct Person: %zu bytes\n", sizeof(struct Person));
      return 0;
  }
  

Size of struct Person: 24 bytes