How do I use standard tools to verify the input of an integer from the console? I want the program to report an error if something like this is entered:
123.3
1223aaw
123 122
Those. only positive and negative integers are allowed.
I tried it myself:
while (!(cin >> k)) { if (cin.fail()) cout << "error" << endl; cin.clear(); cin.ignore(numeric_limits<streamsize>::max(), '\n'); } 
You can read data, and then send it to a special method that will look for invalid characters in the variable.
Regular expressions are well suited for searching for invalid characters.
If there are invalid characters, then return true , and if not, then false , and in the calling code you can already generate an exception via throw .
I found this solution:
#include <iostream> using namespace std; int main() { int length; int width; cout << "Enter the length: "; cin >> length; // input the length cout << "Enter the width: "; cin >> width; // input the width cout << "The area is "; cout << length * width; return 0; } In theory, if you cannot convert the string to an int, an error will crash.
Source: https://ru.stackoverflow.com/questions/567708/
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