How do you calculate integer data type?

Answer 1

To determine the range of an integer data type you first need to know the size of the integer, in bytes. This is implementation-dependant, so never assume it will always be 4 bytes. On a 64-bit system, it could be 4 or 8.

To accurately determine the size of any datatype, always use the sizeof() operator. If you don't, then you are guaranteed to run into major problems when porting programs between compilers and architectures.

Once you have the size, determining the range is fairly easy. The following program contains two function overloads to determine the range of an int and an unsigned int, using bitwise shift operations. The main function tests both functions, showing the ranges in both decimal and hexadecimal (example output is shown below).

#include <iostream>

#include <iomanip>

size_t GetRange(const int& i, int& iMin, int& iMax )

{

int sizeInBits = sizeof(i) * 8;

iMin = 1;

iMin <<= --sizeInBits;

iMax = 1;

while(--sizeInBits)

{

iMax <<= 1;

iMax |= 1;

}

return(sizeof(i));

}

size_t GetRange(const unsigned int& u, unsigned int& uMin, unsigned int& uMax )

{

unsigned int sizeInBits = sizeof(u) * 8;

uMin = 0;

uMax = 1;

while(--sizeInBits)

{

uMax <<= 1;

uMax |= 1;

}

return(sizeof(u));

}

int main()

{

using namespace std;

const int w=17, z=12;

int x, iMin, iMax;

unsigned int y, uMin, uMax;

size_t iSize=GetRange(x, iMin, iMax);

size_t uSize=GetRange(y, uMin, uMax);

cout<<setw(z)<<"Type"<<setw(w)<<"int (x)"<<setw(w)<<"unsigned int (y)"<<endl;

cout<<setw(z)<<"Size (bytes)"<<setw(w)<<iSize<<setw(w)<<uSize<<endl;

cout<<setbase(10);

cout<<setw(z)<<"Min (dec)"<<setw(w)<<iMin<<setw(w)<<uMin<<endl;

cout<<setw(z)<<"Max (dec)"<<setw(w)<<iMax<<setw(w)<<uMax<<endl;

cout<<setbase(16);

cout<<setw(z)<<"Min (hex)"<<setw(w)<<iMin<<setw(w)<<uMin<<endl;

cout<<setw(z)<<"Max (hex)"<<setw(w)<<iMax<<setw(w)<<uMax<<endl;

cout<<endl<<endl;

return(0);

}

Output:

Typeint (x)unsigned int (y)Size (bytes)44Min (dec)-21474836480Max (dec)21474836474294967295Min (hex)800000000Max (hex)7fffffffffffffff

Note the way signed integers are represented in hexadecimal. It looks odd but the binary representation of -1 in 8-bit notation is 11111111 (FFh), not 10000001 (81h) as you might expect. It makes more sense when you realise 11111111+00000001=00000000 which, in decimal, would be -1+1=0.

Answer 2

values can be calculated using the general formula which is given below,

no of values data type can have=2^n(2 power n),where n represents no of bits.

so the value of byte data type=2^8(i.e 1 byte=8 bits),here n=8

byte value=256

Answer 3

• In a 16-bit system, MSB bit is considered as a sign bit. We skip that bit.

• So 16 bits - 1 bits = 15 bits

• Then an Integer value is 2 bytes.

• Max range = 2 raise to 15 ( 215 )

= 32767

• Min range = 2 raise to -15 ( 2-15 )

= -32767

Helen

Answer 4

To calculate this, you would need information about how the information is stored internally in this data type - how many bits for the mantissa, how many for the exponent - and how the bits are interpreted (since there may be an offset).

<><><><><>

You could also include the standard include file FLOAT.H and query the various limits, such as FLT_MAX and FLT_MIN.