QA·C Help - 3709

	3709	Implicit conversion: char to double.

Arithmetic type - Implicit conversions

An expression of type char is being implicitly converted to type double. This is a strange type conversion. Is it intended ?

As shown in the code example below, implicit type conversions of this nature can occur in the context of:

initializations
assignment operations
balancing
the passing of a function argument
the return of a value from a function

In the C language there exist 3 distinct char types:

signed char
unsigned char
char (often referred to as "plain char"

It is recommended that signed char and unsigned char should be used for "numeric" data and plain char should be used for "character" data.

For example:


/*PRQA S 2017,3197,3199,3203,3227,3408,3447,3602,3625 ++*/


extern void ef(double p);

extern double foo(char v)
{
    double a = v;               /* Message 3709 - Initialisation    */

    a = v;                      /* Message 3709 - Assignment        */

    a = a + v;                  /* Message 3709 - Balancing         */

    ef(v);                      /* Message 3709 - Function Argument */

    return v;                   /* Message 3909 - Function Return   */
}

No MISRA C:2012 Rules applicable to message 3709