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How to check if input is numeric in C++?
Here we will see how to check whether a given input is numeric string or a normal string. The numeric string will hold all characters that are in range 0 – 9. The solution is very simple, we will simply go through each characters one by one, and check whether it is numeric or not. If it is numeric, then point to the next, otherwise return false value.
Example
#include <iostream>
using namespace std;
bool isNumeric(string str) {
for (int i = 0; i < str.length(); i++)
if (isdigit(str[i]) == false)
return false; //when one non numeric value is found, return false
return true;
}
int main() {
string str;
cout << "Enter a string: ";
cin >> str;
if (isNumeric(str))
cout << "This is a Number" << endl;
else
cout << "This is not a number";
}Output
Enter a string: 5687 This is a Number
Output
Enter a string: 584asS This is not a number
Updated on: 30-Jul-2019
4K+ Views
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