# C++ Integer promotions

**[Integer promotions](https://en.cppreference.com/w/cpp/language/implicit_conversion)** are automatic type conversions where smaller integer types (`bool`, `char`, `short`) are converted to `int` or `unsigned int` in arithmetic operations. This is an implicit conversion rule from the C standard that C++ inherits, often causing surprises when arithmetic on `char` or `short` unexpectedly produces `int`.

Be aware that arithmetic on `char` or `short` produces `int`; use explicit casts if you need different types.

## Example

This example shows integer promotions in arithmetic operations.

```cpp
// compile: g++ -o promote promote.cpp
// run: ./promote
// description: integer promotions convert small types to int

#include <iostream>
#include <typeinfo>

int main() {
    char c = 'A';
    short s = 10;
    
    auto result_c = c + 1;      // char promoted to int
    auto result_s = s + 1;      // short promoted to int
    
    std::cout << "sizeof(char): " << sizeof(char) << "\n";
    std::cout << "sizeof(c + 1): " << sizeof(result_c) << "\n";
    std::cout << "Type: " << typeid(result_c).name() << "\n";
    
    // Result is int, not char
    std::cout << "c + 1 = " << result_c << "\n";
    
    return 0;
}
```