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When converting integers to floating-point values, and vice versa, it is important to carry out proper range checks to avoid undefined behavior . (See see FLP34-C. Ensure that floating-point conversions are within range of the new type).)

Noncompliant Code Example

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void func(void) {
  short a = 533;
  int b = 6789;
  long c = 466438237;

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

  d /= 7; /* d is 76.14286 */
  e /= 30; /* e is 226.3 */
  f *= 789; /* f is 368019768993.0 */
}

Exceptions

FLP06-C-EX0: It may be desirable to have the operation take place as integers before the conversion (obviating the need for a call to trunc(), for example). If this is the programmer's intention, 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 of precision. Additionally, these unexpected results may actually involve overflow, or undefined behavior.

Automated Detection

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

Bibliography

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