Below is a program written in order to perform a task, trace the program and provide comments for the code. In a few sentences, describe what does the program do? and show the result of the execution:
4-) Below is a
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#include <iostream> #include <cstring> #include <stack> using namespace std; #define maxchars 100//
int main() { char input_str[maxchars+1], *p; stack<double> num_stack; int c; double a, b, n;
cout << "Enter string: "; cin.getline(input_str, maxchars); p = strtok(input_str, " "); while (p) { c = p[0]; if (c == '+' || c == '*' || c == '/' || c == '-') { if (num_stack.size() < 2) { cout << "Error: too many ops." << endl; system("pause"); return -1; } b = num_stack.top(); num_stack.pop(); a = num_stack.top(); num_stack.pop(); switch (c) { case '+': n = a + b; break; case '*': n = a * b; break; case '/': n = a / b; break; case '-': n = a - b; break; } num_stack.push(n); } else { num_stack.push(atof(p));
} p = strtok(NULL, " "); } cout << "The answer is: " << num_stack.top() << endl; system("pause"); return 0; }
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