Calculate Strings with int calculate(string exp) Function

[needOfHelpCMath]

If input is 2: call int calculate(string exp) function. This function will return the
computation of a string expression (exp). For example:
calculate(“54321+222”) will return 54543
calculate(“120*20”) will return 2400
calculate(“235/3”) will return 78
calculate(“356-32”) will return 324My code:

// function should return int, not void: int calculate(..)
int calculate(string exp) 
{
	int answer = 0; // store answer in here
	string left = "right";
	char op; //operator
	int i = 0;
	 // use to code left the operator and right seperating it in order to convert it into real numbers
	for (i = 0; i < exp.size(); ++i) {
		if (isdigit(exp.at(i))) { 
		
			left =  left + exp.at(i);
		}
		
		else {
			op = exp.at(i);
			break;
		}
	} ++i;
	
	for (int j = i; j < exp.size(); ++j) {
		right = "right" + exp.at(i);
	}
	// use ASCII char to get int conversion: '0' == 48, '1' == 49, '2' == 50, ... and so on
	// subtract each character in string by 48 to get int values
	// examle: if exp = "9", then exp[0] - 48 = 9
	
	for(i = 0; i < exp.length(); i++) {
		// put your if statements to check for plus, minus, times, divide
		if (i < exp.length()) {
			answer = exp.at(i)-48;
		}
			
		if (isdigit(exp.at(i))) {
		
			answer = exp.at(i)- 48;
		}
	}
	// check for a plus
		// if found add the two numbers
	// check for minus
		// if found, subtract the two numbers
	// check for a times
		// if found, multiply the two numbers
	// check for divide
		// if found, divide the to numbers
	// if nothing is found
		// return
	return answer;     
}

what I can't and don't understand is how convert into strings into numbers and also compute them.

 

[I like Serena]

what I can't and don't understand is how convert into strings into numbers and also compute them.

Hey needOfHelpCMath! ;)

To convert a string into a number we can use:

int number = atoi(str.c_str());

[m]atoi[/m] is short for ascii-to-integer.

 

[needOfHelpCMath]

Hey needOfHelpCMath! ;)

To convert a string into a number we can use:

int number = atoi(str.c_str());

[m]atoi[/m] is short for ascii-to-integer.

thank you! ill try that out