iswdigit() function in C/C++

The iswdigit() is a built-in function in C++ STL which checks if the given wide character is an decimal digit character or not. It is defined within the cwctype header file of C++. The characters from 0 to 9 i.e.0, 1, 2, 3, 4, 5, 6, 7, 8, 9 are classified as decimal digits.

Syntax:

int iswdigit(ch)

Parameter: The function accepts a single mandatory parameter ch which specifies the wide character which we have to check that if it is a digit or not.

Return Value: The function returns two values as shown below.

• If the ch is a digit, then a non-zero value is returned.
• If it is not then 0 is returned.

Below programs illustrates the above function.

Program 1:

// C++ program to illustrate
// iswdigit() function
#include <cwctype>
#include <iostream>
using namespace std;

int main()
{

    wchar_t ch1 = '?';
    wchar_t ch2 = '3';

    // Function to check if the character
    // is a digit or not
    if (iswdigit(ch1))
        wcout << ch1 << " is a digit ";
    else
        wcout << ch1 << " is not a digit ";
    wcout << endl;

    if (iswdigit(ch2))
        wcout << ch2 << " is a digit ";
    else
        wcout << ch2 << " is not a digit ";

    return 0;
}

Output:

? is not a digit 
3 is a digit

Program 2:

// C++ program to illustrate
// iswdigit() function
#include <cwctype>
#include <iostream>
using namespace std;

int main()
{

    wchar_t ch1 = '1';
    wchar_t ch2 = 'q';

    // Function to check if the character
    // is a digit or not
    if (iswdigit(ch1))
        wcout << ch1 << " is a digit ";
    else
        wcout << ch1 << " is not a digit ";
    wcout << endl;

    if (iswdigit(ch2))
        wcout << ch2 << " is a digit ";
    else
        wcout << ch2 << " is not a digit ";

    return 0;
}

Output:

1 is a digit 
q is not a digit