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Using integer arithmetic to calculate a value for assignment to a floating-point variable may lead to loss of information. This can be avoided by converting one of the integers in the expression to a floating-point type. When converting integers to floating-point values, it is important to be aware that there may be loss of precision (see INT33-J. Do not cast numeric types to wider floating-point types without range checking).

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In this noncompliant code example, the division and multiplication operations take place on integers and the result gets converted to floating-point. This causes floating-point variables d, e, and f to be initialized incorrectly because the operations take place before the values of a, b and c are converted to floating-point. The results of the operations are truncated to the nearest integer or may overflow.

short a = 533;
int b = 6789;
long c = 4664382371590123456L;

float d = a / 7;    // d is 76.0 (truncated)
double e = b / 30;  // e is 226.0 (truncated)
double f = c * 2;   // f is -9.1179793305293046E18 duebecause toof overflow

Compliant Solution (Floating Point Literal)

In this This compliant solution , eliminates the decimal error in initialization is eliminated by ensuring that at least one of the operands to the division operation is of the floating-point type.

short a = 533;
int b = 6789;
long c = 4664382371590123456L;

float d = a / 7.0f;       // d is 76.14286
double e = b / 30.;       // e is 226.3
double f = (double)c * 2; // f is 9.328764743180247E18

Compliant Solution

In this This compliant solution , eliminates the initialization errors are eliminated by first storing the integers in the floating-point variables and then performing the arithmetic operations. This ensures that at least one of the operands is a floating-point number, and consequently the operation is performed on floating-point numbers.

short a = 533;
int b = 6789;
long c = 4664382371590123456L;

float d = a;
double e = b;
double f = c;

d /= 7;   // d is 76.14286
e /= 30;  // e is 226.3
f *= 2;  // f is 9.328764743180247E18

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FLP31-EX1: If it is the programmer's intention to have the operation use integers before the conversion (obviating the need for a call to use the floor() method, for example) it should be clearly documented to help future maintainers understand that this behavior is intentional.

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Improper conversions between integers and floating point values may yield unexpected results, especially loss as a result of precision loss. In some cases, these unexpected results may involve overflow, or undefined behavior.

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