How to use sizeo in c language

The sizeo operator is used to obtain the byte size of a data type or variable, and returns an integer of size_t type indicating the number of occupied bytes. Usage: Allocate memory space: Determine the byte size of a variable or data type. Pass a variable to a function: Get the byte size of the variable. Calculate the size of an array or structure: Calculate the total size in bytes.

sizeo usage in C language

#sizeo operator is used to obtain data types or variables in C language Byte size operators. It returns an integer of type size_t representing the number of bytes occupied by this type or variable in memory.

Syntax

<code>size_t sizeof(data_type or variable);</code>

Where:

• data_type is the data type whose byte size is to be obtained.
• variable is the variable whose size in bytes is to be obtained.

Usage

The sizeo operator is usually used in the following scenarios:

• Allocate memory space: Before allocating memory space, Need to know the byte size of the variable or data type.
• Pass variables to functions: When the function needs to know the byte size of the variable, it can use the sizeo operator to obtain it.
• Calculate the size of an array or structure: The sizeo operator can be used to calculate the total byte size of an array or structure.

Example

<code class="c">#include <stdio.h>

int main() {
  printf("int: %zu bytes\n", sizeof(int));
  printf("float: %zu bytes\n", sizeof(float));
  printf("double: %zu bytes\n", sizeof(double));

  int array[5];
  printf("array: %zu bytes\n", sizeof(array));

  struct student {
    int id;
    char name[50];
  };
  struct student s;
  printf("student: %zu bytes\n", sizeof(s));

  return 0;
}</code>

Output:

<code>int: 4 bytes
float: 4 bytes
double: 8 bytes
array: 20 bytes
student: 54 bytes</code>

Note

##sizeo operation operator will only return the size in bytes of the variable or data type in memory, not including pointers or references.
• The return value of the sizeo operator is an unsigned integer, so it can never be negative.
• sizeo operator cannot be used to get the byte size of a function or block.

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