Updated April 13, 2023
Introduction to C++ size_t
In C++, size_t is defined as the type to represent the object size in bytes which is an unsigned integer type provided by the standard library for representing the object’s size and counting and this is a type returned by the sizeof operator which is also used as the return type of many different cstring functions such as strcspn, strlen, strspn, etc. In general, size_t is the unsigned type which means it can never be negative which is also used for array indexing and counting, this size_t is unsigned mem-size-type which is defined by the standard library of C or C++ programming languages.
Working of size_t in C++
In this article, we will discuss size_t type which is an unsigned integer memsize type which can hold objects of any type having maximum size and is obtained from C or C++ standard library which is a returned type of sizeof operator along with different string functions. The values of any non-member pointers can be saved easily and safely by using size_t type and therefore this type is widely used in array indexing and loop counting. We should note that the size_t type can never hold any negative value. In C++, this size_t type is used widely instead of int or unsigned int. Therefore many use it as unsigned int which is similar to that of size_t unsigned type as both are of integer type of size 16 bits but size_t will easily work for a 64-bit system which actually has the same size as that as big as unsigned long and unsigned int cannot as it will be 32 bit so both cannot be used as interchangeably. Hence size_t is widely used as it is certainly big enough as an array of 4GB which can be larger as unsigned long or to represent the size as large as the largest object in the system and can also store small as int or unsigned int so it the best practice to use size_t type when dealing with a wide range of memory storage.
In C++, there are many different data types where unsigned int can hold 32 bit only but if we nee larger sized object to store then this will fail so there is unsigned long int can also be used but this starts degrading the performance of the system as it works with 32 bits in 16-bit chunks each which needs two machine instructions to execute so it degrades the performance of systems so to overcome all these issues it is easy to use size_t unsigned integer type than the above data types for the objects with the larger size to store in the memory.
This size_t is also returned types of different string and num functions like strcspn, memchr, memcpy, strlen, strspn, etc for returning the sizes and lengths. So we will see in the below example how int data type can have numbers and size_t type.
Examples of C++ size_t
Following are the examples are given below:
Example #1
Code:
#include <iostream>
#include <climits>
using namespace std;
intmain()
{
cout<< "The largest value of the int type can hold is: " << INT_MAX <<endl;
cout<< "\n" <<endl;
cout<< "The smallest value of the int type can hold is: " << INT_MIN <<endl;
cout<< "\n" <<endl;
cout<< "The size the size_t type can hold is: " << (size_t)0 - 1 <<endl;
}Output:
In this above program, we can see that we are printing the largest value of the int type and the lowest value also which the int type can hold where we can see int can hold both positive and negative numbers whereas we can see the size_t type can hold the largest object size in the system but it can have only positive numbers but it can hold much bigger numbers than int type. So using “INT_MAX”, “INT_MIN” we can print the max and min values the int type can hold. So we can see the output with the size of both types in the output of the above code in the screenshot.
Now let us see a sample example of how to use and where to use size_t type in C++ programming languages.
Example #2
Code:
#include <cstddef>
#include <iostream>
#include <array>
intmain()
{
constsize_t s = 500;
int n[s];
size_t size = sizeof(n);
printf("The maximum size of the variable s could be = %lu\n", SIZE_MAX);
printf("\n");
printf("The size_t type used with array of numbers is as follows ");
std::array<std::size_t,15>arr;
for (std::size_t p = 0; p != arr.size(); ++p)
arr[p] = p;
for (std::size_t p = arr.size()-1; p <arr.size(); --p)
std::cout<<arr[p] << " ";
}Output:
In the above program, we can see first we have just declared a variable “s” to display its size.It can hold after defining it with size_t type and we are storing it as an array so to display the size of this array is obtained by “SIZE_MAX” and then we are trying to display the elements of an array type with small numbers as 500 is large to show in the output we have just taken 15 numbers to display. So using this size_t type we are starting with the index 0 so here again, we can see we can use sixe_t for indexing and counting also. Then it will decrement the numbers which means the array is displayed in descending order as we can see in the output in the above screenshot.
Conclusion
In this article, we conclude that in C++ size_t is also an unsigned integer type same as there is unsigned int provided by the C++ standard library where we can even get this size_t type. In C++, the unsigned int and size_t type are considered the same but it is best practice to use size_t when we are trying to use positive and large numbers. In this article, we saw the difference of unsigned int and size_t with the program and we also saw the example where we have declared a variable and also to display the array of numbers.
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