overflow « bit « C Data Type Q&A

1. C language: #DEFINEd value messes up 8-bit multiplication. Why?    stackoverflow.com

I have the following C code:

#define PRR_SCALE 255
...
uint8_t a = 3;
uint8_t b = 4;
uint8_t prr;
prr = (PRR_SCALE * a) / b;
printf("prr: %u\n", prr);

2. Catching overflow of left shift of constant 1 using compiler warning?    stackoverflow.com

We're writing code inside the Linux kernel so, try as I might, I wasn't able to get PC-Lint/Flexelint working on Linux kernel code. Just too many built-in symbols etc. But that's ...

3. How to detect overflow when subtracting two signed 32 bit numbers in C?    stackoverflow.com

I've got two signed integers, and i'd like to subtract them. I need to know if it overflowed.

int one;
int two;
int result = two-one;

if (OVERFLOW) {
    printf("overflow");
} else {
 ...

4. How to calculate 2^n-1 efficiently without overflow?    stackoverflow.com

I want to calculate 2ⁿ-1 for a 64bit integer value. What I currently do is this

for(i=0; i<n; i++) r|=1<<i;

5. how to calculate (a times b) divided by c only using 32-bit integer types even if a times b would not fit such a type    stackoverflow.com

Consider the following as a reference implementation:

/* calculates (a * b) / c */
uint32_t muldiv(uint32_t a, uint32_t b, uint32_t c)
{
    uint64_t x = a;
    x ...

6. Overflow in bit fields    stackoverflow.com

can I trust that the C compiler does modulo 2^n each time I access a bit field? Or is there any compiler/optimisation where a code like the one below would not print ...

7. C: avoiding overflows when working with big numbers    stackoverflow.com

I've implemented some sorting algorithms (to sort integers) in C, carefully using uint64_t to store anything which has got to do with the data size (thus also counters and stuff), since ...

8. Overflow of 32 bit variable    stackoverflow.com

Currently I am implementing an equation (2^A)[X + Y*(2^B)] in one of my applications. The issue is with the overflow of 32 bit value and I cannot use 64 bit ...