Thread: ensure input is only integer

Good day, I was writing a program in C++.I was validating to ensure that only integer is accepted.

that is for int a;
a can take the value of single digit or double digit numbers like (13/123213/2312321).

Is there any way to check,that FOR variable a,
ONLY digits are entered and
NO decimal(like 2.4 1.002) or characted has been inputed?

I'd say you want to grab your input with getine(), which will effectively put the number into a string. Using that you can check for decimals, and then use a stringstream to convert the string back into a number.

If the stringstream conversion fails, what the user entered was probably not a number.

Why not just use cin and check if it failed to read an int?

Code:

int a;

if ( cin >> a ) {
  // it read an int
} else {
  // not an int
}

You can put all of that in a loop:

Code:

cout << "enter an integer> ";

while ( !( cin >> a ) ) {
  cin.clear();
  cin.ignore( 256, '\n' );
  cout << "not an integer; try again> ";
}