Simple calculator using command line with C++

Question

I\'m writing a project that we do simple calculator from command line. The users input in this format programname firstNumber operator secondNumber. Here what I

Answer 1

Here is the problem:

double firstNumber = atoi(argv[1]);
char theOperator = argv[2][0];
double secondNumber = atoi(argv[3]);

atoi converts a string to an int, so 2.5 will be converted to 2 and 1.25 will be converted to 1, that's why you get the result 2 + 1 = 3. Use atof instead.