Rule Definition
When using a floating-point loop counter, the accumulation of rounding errors may result in a mismatch between the expected and actual number of iterations. This can happen when a loop step that is not a power of the floating-point radix is rounded to a value that can be represented. Even if a loop with a floating-point loop counter appears to behave correctly on one implementation, it may give a different number of iterations on another implementation.

Remediation
Use an integral variable

Violation Code Sample

uint32_t counter = 0u;
for ( float32_t f = 0.0f; f < 1.0f; f += 0.001f )
{
++counter;
}

/*The following while loop is non-compliant because f is being used as a loop counter. */
float32_t f = 0.0f;
while ( f < 1.0f )
{
f += 0.001f;
}

Fixed Code Sample

float32_t f;
for ( uint32_t counter = 0u; counter < 1000u; ++counter )
{
f = ( float32_t ) counter * 0.001f;
}


_______________________________________________

/* The following while loop is compliant because f is not being used as a loop counter.*/
float32_t f;
uint32_t u32a;
f = read_float32 ( );
do
{
u32a = read_u32 ( );
/* f does not change in the loop so cannot be a loop counter */
} while ( ( ( float32_t ) u32a - f ) > 10.0f );

MISRA C 2012 - 14.1: A loop counter shall not have essentially floating type AUTOSAR, C++, 2014, Rule A6-5-2: A for loop shall contain a single loop-counter which shall not have floating point type. MISRA, C++, 2008, Rule 6-5-1: A for loop shall contain a single loop-counter which shall not have floating type.