C++ Data Types

C++ Basic Data Types

C++ is a statically typed language, meaning every variable must have a declared type. The type determines what kind of data is stored and how much memory it uses.

Integer Types

Floating-Point Types

#include <iostream>
using namespace std;

int main() {
    int    a = 1000000;
    double b = 3.14159265358979;
    float  c = 3.14f;           // Use 'f' suffix for float literals
    char   d = 'Z';
    bool   e = false;

    cout << "int:    " << a << endl;
    cout << "double: " << b << endl;
    cout << "float:  " << c << endl;
    cout << "char:   " << d << endl;
    cout << "bool:   " << e << endl;
    return 0;
}

Output:

int:    1000000
double: 3.14159265358979
float:  3.14
char:   Z
bool:   0

Checking Type Sizes with sizeof

cout << "int size:    " << sizeof(int)    << " bytes" << endl;
cout << "double size: " << sizeof(double) << " bytes" << endl;
cout << "char size:   " << sizeof(char)   << " bytes" << endl;

Output:

int size:    4 bytes
double size: 8 bytes
char size:   1 bytes

Integer Overflow

If you store a value too large for its type, overflow occurs — the value wraps around unexpectedly:

short x = 32767;
x++;
cout << x;   // Output: -32768 (overflow!)

#include <iostream>
using namespace std;

int main() {
    long long earthPopulation = 8000000000LL;
    double speedOfLight = 299792458.0;
    char firstLetter = 'A';

    cout << "Population: " << earthPopulation << endl;
    cout << "Speed of Light: " << speedOfLight << endl;
    cout << "First Letter: " << firstLetter << endl;
    return 0;
}

Summary

• C++ has several integer types: short, int, long, long long.
• Floating-point types: float, double, long double.
• sizeof(type) returns the number of bytes used.
• Use long long for very large integers to avoid overflow.