...
This compliant solution eliminates the possibility of undefined behavior resulting from a left shift operation on integers, it . It also uses unsigned integers in accordance with INT13-C. Use bitwise operators only on unsigned operands. Smaller sized integers are promoted according to the integer promotion rules (see INT02-C. Understand integer conversion rules).
| Code Block | ||
|---|---|---|
| ||
unsigned int ui1; unsigned int ui2; unsigned int sresult; if ((ui2 >= sizeof(int)*CHAR_BIT) || (ui1 > (INT_MAX >> ui2)) ) { /* handle error condition */ } else { sresult = ui1 << ui2; } |
...
| Code Block | ||
|---|---|---|
| ||
unsigned int ui1 unsigned int ui2 unsigned int uresult; /* modulo behavior is allowed on mod1 and mod2 by exception */ unsigned int mod1 unsigned int mod2; /* ... */ if ( (ui2 >= sizeof(unsigned int)*CHAR_BIT) || (ui1 > (UINT_MAX >> ui2))) ) { /* handle error condition */ } else { uresult = ui1 << ui2; } if (mod2 >= sizeof(unsigned int)*CHAR_BIT) { /* handle error condition */ } else { /* modulo behavior is allowed by exception */ uresult = mod1 << mod2; } |
Noncompliant Code Example (Right Shift)
...