Selecting the appropriate data type is essential for optimizing both the performance and memory usage of a C++ program. Understanding the range and size of each data type allows developers to make informed decisions based on the specific requirements of their application, ensuring efficient and effective code.
Data Type | Memory Size | Minimum Value | Maximum Value |
---|---|---|---|
bool | 1 byte | false (0) | true (1) |
char | 1 byte | -128 | 127 |
unsigned char | 1 byte | 0 | 255 |
short | 2 bytes | -32,768 | 32,767 |
unsigned short | 2 bytes | 0 | 65,535 |
int | 4 bytes | -2,147,483,648 | 2,147,483,647 |
unsigned int | 4 bytes | 0 | 4,294,967,295 |
long | 4 or 8 bytes | -2,147,483,648 to -9,223,372,036,854,775,808 | 2,147,483,647 to 9,223,372,036,854,775,807 |
unsigned long | 4 or 8 bytes | 0 | 4,294,967,295 to 18,446,744,073,709,551,615 |
long long | 8 bytes | -9,223,372,036,854,775,808 | 9,223,372,036,854,775,807 |
unsigned long long | 8 bytes | 0 | 18,446,744,073,709,551,615 |
float | 4 bytes | ~1.2E-38 | ~3.4E+38 |
double | 8 bytes | ~2.3E-308 | ~1.7E+308 |
long double | 8, 12, or 16 bytes | ~3.4E-4932 | ~1.1E+4932 |
char
, short
) when memory conservation is critical, especially in large arrays or embedded systems.float
for single-precision calculations when memory usage is more important than precision. Use double
for double-precision calculations where accuracy is more critical.int
or unsigned int
for loop counters and indices.float
and double
are necessary for calculations requiring fractional values.unsigned int
, unsigned long
) when negative values are not needed, to extend the positive range.long long
or unsigned long long
for very large integers.long
and long double
sizes across platforms. Always verify with the target platform’s specifications.double
or long double
.static_cast
for explicit type conversions to improve code readability and safety.std::int32_t
or std::uint64_t
from <cstdint>
for more explicit type definitions and better cross-platform consistency.