C++ program to check if a given string is valid integer

 

#include <iostream>

using namespace std;

bool isNumber(string s)

{

for (int i = 0; i < s.length(); i++)

if (isdigit(s[i]) == false)

return false;

return true;

}

// Driver code

int main()

{

// Saving the input in a string

string str = "6790";

// Function returns 1 if all elements

// are in range '0-9'

if (isNumber(str))

cout << "Integer";

// Function returns 0 if the input is

// not an integer

else

cout << "String";

}