Tutorial: Integers

This tutorial will teach you how to use integers in C++.

Integers

Integers are whole numbers such as -1, 0, 1, etc

Integers can't have decimal fractions :

Integer: 44
Float: 44.551

Round Down ( Truncation )

When a floating point number is assigned to an integer variable, the decimal fraction is removed.

This is called truncation :

#include <iostream>
using namespace std;
 
int main()
{
    int   int_var = 5.22;
    float flo_var = 5.22;
    cout << "int_var = " << int_var << endl;
    cout << "flo_var = " << flo_var << endl;
    return 0;
}

If you need the decimal fraction included, use a float variable instead of an integer variable.

Integer Division

Whenever two integers are divided, the answer is always an integer, never a floating point number.

This is called integer division :

#include <iostream>
using namespace std;
 
int main()
{
    cout << "5 / 2 = " << 5 / 2 << endl;
    return 0;
}

Only if one or both of the numbers involved in the division is a floating point number will the decimal fraction be included :

#include <iostream>
using namespace std;
 
int main()
{
    cout << "5 / 2 = " << 5 / 2.0 << endl;
    return 0;
}

Note that 2.0 is a floating point number, even though it has the same value as 2.

#include <iostream>
using namespace std;
 
int main()
{
    if ( 2 == 2.0 )
    {
        cout << "2 equals 2.0" << endl;
    }
    else
    {
        cout << "2 does not equal 2.0" << endl;
    }
}

Limits

There are three kinds of integer variables : short, int, and long.

Each can be signed or unsigned.

Each of these has a minimum and maximum value :

Integer Type Minimum Value Maximum Value
short (signed) -32767 32767
short unsigned 0 65535
int (signed) -32767 32767
int unsigned 0 65535
long (signed) -2147483647 2147483647
long unsigned 0 4294967295 
#include <iostream>
using namespace std;
 
int main()
{
    short sshrt_var = 32767;
    short unsigned ushrt_var = 65535;
    int sint_var = 32767;
    int unsigned uint_var = 65535;
    long slong_var = 2147483647;
    long unsigned ulong_var = 4294967295;
 
    cout << "short (signed) : " << sshrt_var << endl;
    cout << "short unsigned : " << ushrt_var << endl;
    cout << "int (signed)   : " << sint_var  << endl;
    cout << "int unsigned   : " << uint_var  << endl;
    cout << "long (signed)  : " << slong_var << endl;
    cout << "long unsigned  : " << ulong_var << endl;
    return 0;
}
Categories: Beginner Tutorials : Tutorials
Footnotes
page_revision: 10, last_edited: 1245913365|%e %b %Y, %H:%M %Z (%O ago)
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