C++ is a strongly typed language. Data types are used to tell the compiler which type of data a variable will hold, which determines the size and layout of that variable's memory.

Always! Every variable in C++ must have a type.

• Access: $O(1)$
• Assignment: $O(1)$

cpp Standard
int age = 25;              // Integer
float temp = 98.6f;        // Floating point
double pi = 3.14159;       // Double precision
char grade = 'A';          // Character
bool isCracked = true;     // Boolean

• Overflow: Storing a value larger than the type can hold.
• Precision loss: Using float when double is needed for high accuracy.
• Mixing signed and unsigned types in comparisons.