#include <iostream> #include <cmath> // Include cmath for rounding using namespace std; // Define the maximum size of the stack const int MAX_SIZE = 100; // Define a stack class using an array class Stack { public: Stack() { top = -1; } bool isEmpty() { return top == -1; } bool isFull() { return top == MAX_SIZE - 1; } void push(char c) { if (!isFull()) { stackArray[++top] = c; } } char pop() { if (!isEmpty()) { return stackArray[top--]; } return '\0'; // Return null character if the stack is empty } char peek() { if (!isEmpty()) { return stackArray[top]; } return '\0'; // Return null character if the stack is empty } private: char stackArray[MAX_SIZE]; int top; }; // Function to perform arithmetic operations double performOperation(double operand1, double operand2, char op) { switch (op) { case '+': return operand1 + operand2; case '-': return operand1 - operand2; case '*': return operand1 * operand2; case '/': if (operand2 != 0) { return operand1 / operand2; } else { cout << "Error: Division by zero" << endl; exit(1); } default: cout << "Error: Invalid operator" << endl; exit(1); } } // Function to check if a character is a digit bool isDigit(char c) { return c >= '0' && c <= '9'; } // Function to calculate the length of a C-style string int stringLength(const char* str) { int length = 0; while (str[length] != '\0') { length++; } return length; } // Function to evaluate an expression using the PEMDAS rule double evaluateExpression(const char* expression) { Stack operandStack; Stack operatorStack; int length = stringLength(expression); for (int i = 0; i < length; i++) { char currentChar = expression[i]; if (isDigit(currentChar)) { double operand = currentChar - '0'; while (i + 1 < length && (isDigit(expression[i + 1]) || expression[i + 1] == '.')) { if (isDigit(expression[i + 1])) { operand = operand * 10 + (expression[i + 1] - '0'); } else if (expression[i + 1] == '.') { double decimalFactor = 0.1; while (i + 2 < length && isDigit(expression[i + 2])) { operand += (expression[i + 2] - '0') * decimalFactor; decimalFactor *= 0.1; i++; } } i++; } operandStack.push(operand); } else if (currentChar == '(') { operatorStack.push(currentChar); } else if (currentChar == ')') { while (!operatorStack.isEmpty() && operatorStack.peek() != '(') { char op = operatorStack.pop(); double operand2 = operandStack.pop(); double operand1 = operandStack.pop(); double result = performOperation(operand1, operand2, op); operandStack.push(result); } operatorStack.pop(); // Pop the '(' } else if (currentChar == '+' || currentChar == '-' || currentChar == '*' || currentChar == '/') { while (!operatorStack.isEmpty() && operatorStack.peek() != '(' && ((currentChar == '+' || currentChar == '-') && (operatorStack.peek() == '*' || operatorStack.peek() == '/'))) { char op = operatorStack.pop(); double operand2 = operandStack.pop(); double operand1 = operandStack.pop(); double result = performOperation(operand1, operand2, op); operandStack.push(result); } operatorStack.push(currentChar); } } while (!operatorStack.isEmpty()) { char op = operatorStack.pop(); double operand2 = operandStack.pop(); double operand1 = operandStack.pop(); double result = performOperation(operand1, operand2, op); operandStack.push(result); } return operandStack.pop(); } int main() { char expression[MAX_SIZE]; cout << "Enter a math expression: "; cin.getline(expression, MAX_SIZE); double result = evaluateExpression(expression); cout << "Result: " << result << endl; return 0; }
Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++
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OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.
#include <iostream>
#include <string>
using namespace std;
int main()
{
string name;
cout << "Enter name:";
getline (cin, name);
cout << "Hello " << name;
return 0;
}
C++ is a widely used middle-level programming language.
When ever you want to perform a set of operations based on a condition If-Else is used.
if(conditional-expression) {
//code
}
else {
//code
}
You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.
Switch is an alternative to If-Else-If ladder.
switch(conditional-expression){
case value1:
// code
break; // optional
case value2:
// code
break; // optional
......
default:
code to be executed when all the above cases are not matched;
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
//code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while (condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.
return_type function_name(parameters);
function_name (parameters)
return_type function_name(parameters) {
// code
}