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unsigned long cannot hold the correct number over 2,147,483,647

By : Amanjit Sahu
Date : July 31 2020, 03:00 PM
this will help The type of the expression 0x80 << 24 is not unsigned long, it’s int. You then assign the result of that expression to P, and in the process convert it to an unsigned long. But at that point it has already overflown (incidentally causing undefined behaviour). Use unsigned long literals in your expression:
code :
P = 0x80ul << 24;

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Break loop on greater number then unsigned long long

By : bomini
Date : March 29 2020, 07:55 AM
Hope that helps If n is unsigned long long then n <= ULLONG_MAX is always true.
If you know that revert always returns a positive number you can check if n + revert( n ) is < n (i.e., check a wrap around). Or also check that revert(n) < ULLONG_MAX - n.

How can I represent a certain number of seconds (minutes) with the type unsigned long long int in C++

By : Chau Lao De
Date : March 29 2020, 07:55 AM
Does that help What are you expecting frequency.QuadPart/1000000 to do?
I think you're looking for something like this?
code :
LARGE_INTEGER startTime, endTime, freq;

QueryPerformanceFrequency(&freq); // freq holds the number of ticks in 1 second.
freq.QuadPart *= 8; // and now in 8 seconds.



    if((endTime.QuadPart - startTime.QuadPart) >= freq.QuadPart)
        // 8 seconds have passed.

    // do something.

Get the minimum number of bytes necessary to hold a given unsigned integer

By : Deva
Date : March 29 2020, 07:55 AM
seems to work fine I need to write a series of unsigned integers to a file, each one being no greater than a limit n determined at runtime. To save space, I want to pack them in as little bytes as possible. However, I've no idea how to compute the minimum number of bytes necessary to hold them, so I only have the following, ugly solution: , You might try something along these lines (untested).
code :
int GetNeededBytes(uint32_t n)
    // Maximum number of bytes supported
    int bytes = 4;
    // Get mask for highest order byte
    // Warning: watch for overflow here
    // 4 bytes should resolve to 0xff000000
    int mask = 0xff << (bytes * 8);

    while (bytes > 0)
        if (n & mask)
            return bytes;
        mask /= 0x100;
    return 0;

Strange behavior when attempting to obtain number of digits of unsigned long long´s maximum

By : WolfpawUK
Date : March 29 2020, 07:55 AM
help you fix your problem IIUC, the OQ wants the size needed to print the maximum values in decimal. The below works for sizes of 8 bits upto 64 bits, at least for CHAR_BIT==8 :
code :
#include <stdio.h>
#include <limits.h>

#define ASCII_SIZE(s) ((3+(s) * CHAR_BIT) *4 / 13)

int main(void)
printf("unsigned char : %zu\n", ASCII_SIZE(sizeof(unsigned char)) );
printf("unsigned short int : %zu\n", ASCII_SIZE(sizeof(unsigned short int)) );
printf("unsigned int : %zu\n", ASCII_SIZE(sizeof(unsigned int)) );
printf("unsigned long : %zu\n", ASCII_SIZE(sizeof(unsigned long)) );
printf("unsigned long long : %zu\n", ASCII_SIZE(sizeof(unsigned long long)) );

printf("          Ding : %u\n", UINT_MAX );
printf("     Lang Ding : %lu\n", ULONG_MAX );
printf("Heel lang Ding : %llu\n", ULLONG_MAX );

return 0;
unsigned char : 3
unsigned short int : 5
unsigned int : 10
unsigned long : 20
unsigned long long : 20
          Ding : 4294967295
     Lang Ding : 18446744073709551615
Heel lang Ding : 18446744073709551615

Problem of using unsigned long long int and long long int in program to calculate power of number

By : mindleaving
Date : March 29 2020, 07:55 AM
wish of those help I have written two functions to find power of positive and negative number in c but it is not printing anything , You're not actually calling the functions:
code :
    void Calculate_neg_power(number,expo);
    void Calculate_pos_power(number,expo);
int Driver(NUMBER,EXPO, ans);
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