isdigit() - Character Function

How is "isdigit()" used in C++?


isdigit() function is used to check the character whether it is between 0-9 or a decimal. It returns zero when the argument is not a decimal or an integer in the given range.


int isdigit ( int c );

Example :

#include <iostream.h>
#include <ctype.h>
int main()
char a;
cout<< "Enter a digit between 0-9: ";
cin >> a;
if (isdigit(a))
cout << "Entered a digit\n";
cout << "Not a digit\n";
return 0;

Result :

Enter a digit between 0-9 : e
Not a digit

In the above example, this function is used to check if the entered character is a decimal or not. It has been checked using ASCII values.

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