Here are a few title options, focusing on the question aspect you requested: Direct and Clear: * What Type Promotions Occur in C/C Variadic Functions? * How Are Arguments Promoted in Variadic Func

Default Type Promotions in Variadic Argument Lists

In C and C , when passing arguments to a function with a variable number of arguments (i.e., a variadic function), certain default type promotions occur.

Integer Promotion

The C and C standards guarantee that any integer type with a rank less than int is promoted to either int or unsigned int. This means that if you pass an 8-bit integer (e.g., uint8_t) to a function that expects int (which is typically 16 bits or more in size), the 8-bit integer will be automatically promoted to 16 bits or larger.

For example, in the provided code snippet:

uint8_t a = 5;
printf("%d", a);

The format specifier %d expects an int, but since a is a uint8_t, it will be promoted to int before being passed to printf.

Float Promotion

Similarly, float values are promoted to double by default. This means that if you pass a float to a function that expects a double, the float will be automatically converted to double precision.

Example

In summary, the default type promotions in variadic argument lists are:

• Every integer type with rank less than int is promoted to int or unsigned int.
• float values are promoted to double.

The above is the detailed content of Here are a few title options, focusing on the question aspect you requested: Direct and Clear: * What Type Promotions Occur in C/C Variadic Functions? * How Are Arguments Promoted in Variadic Func. For more information, please follow other related articles on the PHP Chinese website!