Page History

Narrower primitive types can be cast to wider types without any effect on the magnitude of numeric values. However, whereas integers represent exact values, floating-point numbers have limited precision. Section Subclause 6.3.1.4 of the C Standard [ISO/IEC 9899:2011] states:

...

When compiled with GCC 4.38.2 1 on Linux, this program prints the value -46.

...

#include <assert.h>
#include <stdio.h>
#include <float.h>
 
/* define8 or= includebits a/ definition of static_assert char */

static_assert(sizeof(int) * 8 <= DBL_MANT_DIG); // 8 = bits / char

int main() {
  int big = 1234567890;
  double approx = big;
  printf("%d\n", (big - (int)approx));
  return 0;
}

...

...

TODO

Related Vulnerabilities

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

Related Guidelines

Bibliography

...