C++ signed Keyword

The signed keyword in C++ is a type modifier used to explicitly declare signed integer data types. A signed integer can represent both positive and negative numbers, including zero. By default, integer data types in C++ are signed unless explicitly declared as unsigned.

The signed keyword can be used with integer data types such as int, short, long, and long long.

Syntax

</>
Copy
signed data_type variable_name;
signed
The keyword indicating that the variable can hold both positive and negative values.
data_type
The integer type, such as int, short, long, or long long.
variable_name
The name of the variable being declared.

Examples

Example 1: Declaring and Initializing signed Variables

In this example, we will declare and initialize signed variables in C++.

</>
Copy
#include <iostream>
using namespace std;

int main() {
    signed int a = 100;       // Signed integer
    signed short b = -50;     // Signed short integer
    signed long c = 100000;   // Signed long integer

    cout << "Signed int a: " << a << endl;
    cout << "Signed short b: " << b << endl;
    cout << "Signed long c: " << c << endl;

    return 0;
}

Output:

Signed int a: 100
Signed short b: -50
Signed long c: 100000

Explanation:

  1. The variable a is a signed integer and can hold both positive and negative values.
  2. The variable b is a signed short integer with a smaller range than int.
  3. The variable c is a signed long integer with a larger range than int.

Example 2: Comparing signed and unsigned Variables

In this example, we will look into the difference between signed and unsigned variables.

</>
Copy
#include <iostream>
using namespace std;

int main() {
    signed int signedVar = -10;      // Signed integer
    unsigned int unsignedVar = 10;  // Unsigned integer

    cout << "Signed variable: " << signedVar << endl;
    cout << "Unsigned variable: " << unsignedVar << endl;

    return 0;
}

Output:

Signed variable: -10
Unsigned variable: 10

Explanation:

  1. The variable signedVar is a signed integer and can hold negative values.
  2. The variable unsignedVar is an unsigned integer and cannot hold negative values.
  3. The output illustrates the difference between signed and unsigned integers.

Example 3: Overflow Behavior with signed Variables

In this example, we will see the behavior of signed variables when they exceed their range.

</>
Copy
#include <iostream>
using namespace std;

int main() {
    signed short value = 32767; // Maximum value for signed short
    cout << "Value: " << value << endl;

    value = value + 1; // Overflow occurs
    cout << "Value after overflow: " << value << endl;

    return 0;
}

Output:

Value: 32767
Value after overflow: -32768

Explanation:

  1. The variable value is initialized to the maximum value of a signed short, 32767.
  2. Adding 1 to value causes an overflow, and the value wraps around to the minimum of the range, -32768.
  3. This behavior demonstrates the limitations of signed integer types.

Key Points about signed Keyword

  1. The signed keyword is used to declare variables that can store both positive and negative values.
  2. It can be used with int, short, long, and long long types.
  3. By default, integer types are signed unless explicitly declared as unsigned.
  4. Signed integers have a range that includes both positive and negative numbers.