In C++, you can check if a value is null or not using pointers or by comparing the value directly.
1. Checking for Null Pointer:
To determine if a pointer is null or not, you can use the pointer value itself. If the pointer is null, it will have a value of 0 or nullptr.
``c++
int* ptr = nullptr; // pointer is explicitly set to null
if (ptr == nullptr) {
std::cout << "Pointer is null\n"; // Output: Pointer is null
}
Or you can use the shorthand notation of which checks if the pointer is pointing to any address or not:
c++
int* ptr = nullptr;
if (!ptr) {
std::cout << "Pointer is null\n"; // Output: Pointer is null
}
c++bool
2. Checking for true/false value:To check if a value is true or false, you can use the
data type. In C++, thetruevalue is represented by 1, whilefalseis represented by 0.
bool a = true;
bool b = false;
if (a) {
std::cout << "a is true\n"; // Output: a is true
}
if (!b) {
std::cout << "b is false\n"; // Output: b is false
}
You can also use comparison operators to check if a value is true or false:
int x = 10;
if (x > 5) {
std::cout << "x is true\n"; // Output: x is true
}
if (x == 0) {
std::cout << "x is false\n"; // This condition will not be met
}
``
Note that any non-zero value is equivalent to true, while zero is equivalent to false.