Difference between long int and long long int in C/C++

All variables use data type during declarations lớn restrict the type of data lớn be stored. Therefore, we can say that data types are used lớn tell the variables the type of data it can store. Whenever a variable is defined in C++, the compiler allocates some memory for that variable based on the data type with which it is declared. Different data types require a different amount of memory.

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Integer: The từ khóa used for integer data types is int. Integers typically require 4 bytes of memory space and range from -2147483648 lớn 2147483647.

Datatype Modifiers: As the name implies, datatype modifiers are used with the built-in data types lớn modify the length of data that a particular data type can hold.

Below is a list of ranges along with the memory requirements and format specifiers on the 32-bit GCC compiler.

S. No.	Data Type	Memory (bytes)	Range
1	int	4	-2^31 lớn 2^31- 1
2	Long int	4	-2^31 lớn 2^31 – 1
3	Long long int	8	-2^63 lớn 2^63 – 1

Long long takes the double memory as compared lớn long. But it can also be different on various systems. Its range depends on the type of application. The guaranteed minimum usable bit sizes for different data types:

char: 8
short:16
int: 16
long: 32
long long: 64

The decreasing order is: long long >=long>=int>=short>=char

Program 1:

In various competitive coding platforms, the constraints are between 10⁷ lớn 10¹⁸. Below is the program lớn understand the concept:

C++

#include <iostream>

using namespace std;

int main()

{

int p = 100000;

int q = 100000;

int result = p * q;

cout << result << endl;

return 0;

}

As above, the output is not correct as int can’t store a 10¹⁰ value(out of its range). In this case, long long should be used.

Program 2:

Below is the C++ program lớn demonstrate how converting int lớn long long affects the output:

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C++

#include <iostream>

using namespace std;

int main()

{

int p = 100000;

int q = 100000;

long long int result = p * q;

cout << result << endl;

return 0;

}

Explanation: The above program gives the same output even after converting int lớn long long int because at first, the result is declared as long long. But before assigning the value of multiplication of p and q, it is already overflowed. Now, lớn prevent the overflow condition, it is required lớn convert the int result lớn the long long int before assigning the result value so sánh that the overflow condition does not occur.

Program 3:

Below is the C++ program lớn implement the above approach:

C++

#include <iostream>

using namespace std;

int main()

{

int p = 100000;

int q = 100000;

long long int result = (long long int)p * q;

cout << result << endl;

return 0;

}

Explanation: After this, it gives the correct output, which is 10¹⁰, which can be easily stored into a long long data type as the range is up lớn 10¹⁸.

Difference between long int and long long int in C/C++ in tabular form:

Feature	long int	long long int
Size	4 bytes on most systems.	8 bytes on most systems.
Syntax	long int x;	long long int x;
Range	-2^31 lớn 2^31 – 1	-2^63 lớn 2^63 – 1
Format specifier	%li	%lli
Usage	Used for storing integers with medium range.	Used for storing integers with large range.