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In this noncompliant example, an object of type float is incremented through an int *.  Using the maximum units in last position is often done as a way The unit in the last place can be used to get the next representable value for a floating-point numbertype.  However, accessing an object through a pointer of incompatible types is undefined behavior.

#include <stdio.h>
 
void f(void) {
  if (sizeof(int) == sizeof(float)) {
    float f = 0.0f;
    int *ip = (int *)&f;
 
    printf("float is %f\n", f);
 
    (*ip)++;
 
    printf("float is %f\n", f);
  }
}

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In this noncompliant code example, an array of two shorts values of type short is treated as an integer and assigned an integer value. The resulting value of the two shorts is undefinedvalues are indeterminate.

#include <stdio.h>
 
void func(void) {
  short a[2];
  a[0]=0x1111;
  a[1]=0x1111;

  *(int *)a = 0x22222222;

  printf("%x %x\n", a[0], a[1]);
}

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Noncompliant Code Example

In this noncompliant code example, a gadget object is allocated, then realloc() is called to create a widget object using the memory from the gadget object. Although reusing memory to change types is acceptable, accessing the memory copied from the original object is undefined behavior.

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