Method 1: Do it yourself and have plenty of food and clothing.
Tip: Just convert the input binary number string into decimal, so the focus is on the to_decimal function.
# include & ltiostream & gt
# include & lt string & gt
# include & ltiomanip & gt
# include & lt restrictions & gt
Use namespace std
//Use long integer to correctly express the integer represented by the binary number string to the maximum extent.
Typedef unsigned long ulong
//The maximum bit of a long integer is usually 32 bits, which is the same as an int on windows.
const ulong max _ digit = numeric _ limits & lt； Ulong & gt* number;
//Check the input
The string check _ input ();
//Convert a string binary number into a decimal number
Ulong to_decimal (constant string & binary);
int main()
{
string binary = check _ input()；
Ulong decimal = to_decimal (binary);
cout & lt& ltendl
Cout.setf (IOs _ base:: left | IOs _ base:: showbase | IOs _ base:: uppercase);
cout & lt& ltsetw( 15)& lt； & lt" Binary "<& lt":" & lt& lt binary & lt& ltendl.
cout & lt& ltsetw( 15)& lt； & lt" Decimal "<& lt":" & lt& lt decimal & lt& ltendl.
//You can use different input/output operators to control input/output formats, such as oct and hex.
cout & lt& ltsetw( 15)& lt； & lt "octal"< ":"<< oct<< decimal & lt& ltendl.
cout & lt& ltsetw( 15)& lt； & lt "hexadecimal"<& lt":" & lt& lt hexadecimal & lt& lt decimal & lt& ltendl.
cout & lt& ltendl
}
//Check whether the input binary number string is qualified.
String check_input ()
{
Cout & lt& lt "Please enter a binary number:";
String binary;
do
{
Getline(cin, binary);
//Check whether the input is empty.
if(binary.empty())
Cout & lt& lt "null input! Try again:';
//Check whether characters other than 0 and 1 are entered.
else if(binary . find _ first _ not _ of(" 10 ")！ = string::NPO)
Cout & lt& lt "You cannot enter other characters"
& lt& lt "except 0 and 1. \ nPlease try again:';
//Check whether the length of the input character exceeds the maximum number of digits that can be represented.
else if(binary . size()>； max_digit)
Cout & lt& lt "You can only enter"<& ltmax _ digit & lt& lt "the number of digits."
& lt< \ nPlease try again: ";
other
Break;
}while (true);
//Returns the checked binary number string.
Returns binary;
}
//Converts a string of binary digits to decimal digits.
Ulong to_decimal (constant string & binary)
{
typedef string::const _ reverse _ iterator rite；
ulong decimal = 0；
for(rite rit = binary . Rb egin()； rit！ = binary . rend()； ++rit)
{
if(*rit == '0 ')
{
Decimal & gt& gt= 1;
}
other
{
Decimal & gt& gt= 1;
decimal | = 0x80000000
}
}
Decimal & gt> = max _ digit-binary. size ();
Returns a decimal;
}
Method 2: Use the powerful standard library of C++ to realize it.
# include & ltiostream & gt
# include & lt string & gt
# include & ltiomanip & gt
# include & lt restrictions & gt
# include & ltbitset & gt// Use standard location set.
Use namespace std
//Use long integer to correctly express the integer represented by the binary number string to the maximum extent.
Typedef unsigned long ulong
//The maximum bit of a long integer is usually 32 bits, which is the same as an int on windows.
const ulong max _ digit = numeric _ limits & lt； Ulong & gt* number;
//Check the input
The string check _ input ();
int main()
{
string binary(check _ input())；
//Convert to 10 decimal number
Ulong decimal = bitset & lt numerical limit & ltulong & gt* number & gt (binary). to _ ulong()；
cout & lt& ltendl
Cout.setf (IOs _ base:: left | IOs _ base:: showbase | IOs _ base:: uppercase);
cout & lt& ltsetw( 15)& lt； & lt" Binary "<& lt":" & lt& lt binary & lt& ltendl.
cout & lt& ltsetw( 15)& lt； & lt" Decimal "<& lt":" & lt& lt decimal & lt& ltendl.
//You can use different input/output operators to control input/output formats, such as oct and hex.
cout & lt& ltsetw( 15)& lt； & lt "octal"< ":"<< oct<< decimal & lt& ltendl.
cout & lt& ltsetw( 15)& lt； & lt "hexadecimal"<& lt":" & lt& lt hexadecimal & lt& lt decimal & lt& ltendl.
cout & lt& ltendl
}
//Check whether the input binary number string is qualified.
String check_input ()
{
Cout & lt& lt "Please enter a binary number:";
String binary;
do
{
Getline(cin, binary);
//Check whether the input is empty.
if(binary.empty())
Cout & lt& lt "null input! Try again:';
//Check whether characters other than 0 and 1 are entered.
else if(binary . find _ first _ not _ of(" 10 ")！ = string::NPO)
Cout & lt& lt "You cannot enter other characters"
& lt& lt "except 0 and 1. \ nPlease try again:';
//Check whether the length of the input character exceeds the maximum number of digits that can be represented.
else if(binary . size()>； max_digit)
Cout & lt& lt "You can only enter"<& ltmax _ digit & lt& lt "the number of digits."
& lt< \ nPlease try again: ";
other
Break;
}while (true);
//Returns the checked binary number string.
Returns binary;
}