Chapter 7 Pointers Question 4

topic:

Use the main function with parameters to implement a calculator that completes integer operations.

For example, if you enter calc 5 * 3, the execution result is 15.

Code:

#include <iostream>
using namespace std;
int main(int argc, char *argv[])
{
	int num1 = 0, num2 = 0, i;

	for (i = 0; argv[1][i] != '\0'; ++i) num1 = num1 * 10 + argv[1][i];
	for (i = 0; argv[3][i] != '\0'; ++i) num2 = num2 * 10 + argv[3][i];

	switch (argv[2][0])
	{
	case '+': cout << (num1 - 48) + (num2 - 48) << endl; break;
	case '-': cout << (num1 - 48) - (num2 - 48) << endl; break;
	case '*': cout << (num1 - 48) * (num2 - 48) << endl; break;
	case '/': cout << (num1 - 48) / (num2 - 48) << endl; break;
	default: cout << "error" << endl;
	}
	
	system("pause");
	return 0;
}