hi, ive got a problem with a calculator ive been writing, ive managed to get user input separated into numbers and operators, but i cant get the numbers to calculate properly.

here is the code.
 ``123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256`` ``````#include #include #include #include using namespace std; int hexstringtoint(string str) { string temp; int * array; temp.clear(); temp = str; int ret = 0; int size; size = temp.length() ; array = new int[size]; for(int i = 0; i < size;i++) { switch(temp[i]) { case '0': array[i] = 0; break; case '1': array[i] = 1; break; case '2': array[i] = 2; break; case '3': array[i] = 3; break; case '4': array[i] = 4; break; case '5': array[i] = 5; break; case '6': array[i] = 6; break; case '7': array[i] = 7; break; case '8': array[i] = 8; break; case '9': array[i] = 9; break; case 'a': array[i] = 10; break; case 'A': array[i] = 10; break; case 'b': array[i] = 11; break; case 'B': array[i] = 11; break; case 'c': array[i] = 12; break; case 'C': array[i] = 12; break; case 'd': array[i] = 13; break; case 'D': array[i] = 13; break; case 'e': array[i] = 14; break; case 'E': array[i] = 14; break; case 'f': array[i] = 15; break; case 'F': array[i] = 15; break; } } for(int i = 0,j = size;i < size;i++,j--) { ret += array[i] * pow(16,static_cast(j)-1); } delete [] array; return ret; } string inttohexstring(int dec) { string sresult = ""; int * iresult = new int [sizeof(dec)]; int remainder = 0; int quotient = 0; int i = 0; bool over = false; int number = dec; string array[] = {"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"}; while(number != 0) { remainder = number % 16; number = number / 16; iresult[i] = remainder; sresult = array[remainder] + sresult; i++; } delete [] iresult; return sresult; } int main() { string input1,input2; char op,exit; int result; bool over = false,invalidanswer = true; string input; string number; int * num; string operators; int numofoperators = 0; int sizeofinput; bool done = false; int counter1 = 0, counter2 = 0; int decanswer = 0; string hexanswer = ""; cout << ":Hexadecimal calculator:" << endl; cout << "------------------------" << endl; while(! over) { decanswer = 0; counter1 = 0; counter2 = 0; number = ""; input = ""; operators = ""; numofoperators = 0; cout << "Enter an equation (don't use spaces)" <"; getline(cin,input); sizeofinput = input.length(); num = new int [sizeofinput]; for(int i = 0;i < sizeofinput;i++) { if(input[i] == '+') { numofoperators++; operators += '+'; } else if(input[i] == '-') { numofoperators++; operators += '-'; } else if(input[i] == '*') { numofoperators++; operators += '*'; } else if(input[i] == '/') { numofoperators++; operators += '/'; } else if(input[i] == '%') { numofoperators++; operators += '%'; } } done = false; while(! done) { if(input[counter1] == ' ' || input[counter1] == '+' || input[counter1] == '*' || input[counter1] == '-' || input[counter1] == '/' || input[counter1] == '%') { counter1++; num[counter2] = hexstringtoint(number); if(input[counter1 + 1] != ' ' || input[counter1 + 1] != '+' || input[counter1 + 1] != '*' || input[counter1 + 1] != '-' || input[counter1 + 1] != '/' || input[counter1 + 1] != '%' || input[counter1 + 1]) { counter2++; number = ""; } } else { number += input[counter1]; counter1++; } if(input[counter1] == '\0') { done = true; num[counter2] = hexstringtoint(number); number = ""; } } //----------------------------------------------- //i think the problem is here-------------------- //----------------------------------------------- for(int i = 0;i != sizeofinput;i+=2) { switch(operators[i]) { case '+': decanswer += num[i] + num[i+1]; break; case '-': decanswer += num[i] - num[i+1]; break; case '*': decanswer += num[i] * num[i+1]; break; case '/': decanswer += num[i] / num[i+1]; break; case '%': decanswer += num[i] % num[i+1]; break; } } cout << "Answer in dec:" << decanswer <> exit; if(exit == 'y' || exit == 'Y') { over = true; invalidanswer = false; } else if(exit == 'n' || exit == 'N') { over = false; invalidanswer = false; } else { cout << endl << "Invalid answer... try again." << endl; invalidanswer = true; } } delete [] num; cin.ignore(); } return 0; }``````

edit: its when i input an uneven amount of numbers that they dont calculate properly
Last edited on
In case of an odd number of numbers you should tell the user that he did something wrong.

But there's another problem:
On line 199 `operators` depends on `sizeofinput`, but it really depends on `numofoperators`
is there any way to make it calculate an odd number of numbers
You mean something like that: 1 + 2 + 3?

without taking precedence into account and the input is correct, it would look like this:
 ``1234567891011121314151617181920212223`` `````` for(int i = 0;i < numofoperators; i++) { switch(operators[i]) { case '+': num[i+1] += num[i]; break; case '-': num[i+1] -= num[i]; break; case '*': num[i+1] *= num[i]; break; case '/': num[i+1] /= num[i]; break; case '%': num[i+1] %= num[i]; break; } } cout << "Answer in dec:" << num[numofoperators] <
thank you, its working now.
i tested it with division and subtraction last night and it keeps giving the wrong answer and i cant figure out how to get it working properly,it works fine with addition and multiplication,but with division and subtraction its just not giving the correct answer
Just for my education, what is the difference between a static cast like this:

`static_cast<double>(j)`

and an ordinary c cast like this:

`(double) j`

I read the documentation, but I don't see what the difference is.

ive got the calculator working, i changed the code in the loop a bit:

 ``1234567891011121314151617181920212223242526`` ``````int temp = num[0]; for(int i = 0,j = 0;i < numofoperators;i++) { switch(operators[i]) { case '+': temp = num[i+1] += num[i]; break; case '-': temp = num[i] -= num[i+1]; break; case '*': temp = num[i+1] *= num[i]; break; case '/': temp = temp / num[i+1]; break; case '%': temp = temp % num[i+1]; break; } } cout << "Answer in dec:" << temp <

@TheIdeasMan i dont know what the difference is.
 ive got the calculator working, i changed the code in the loop a bit:
Unfortunately that's wrong too.

While the idea with temp is right since my previous approach didn't take the order into account.

The following gives the correct answer for 1 + 2 - 3 + 4 - 5 + 6:
 ``12345678910111213141516171819202122232425`` ``````int temp = num[0]; for(int i = 0,j = 0;i < numofoperators;i++) { switch(operators[i]) { case '+': temp += num[i+1]; break; case '-': temp -= num[i+1]; break; case '*': temp *= num[i+1]; break; case '/': temp /= num[i+1]; break; case '%': temp %= num[i+1]; break; } } cout << "Answer in dec:" << temp <

@TheIdeasMan
static_cast cannot cast away const and other 'attributes' while the c style cast doesn't care
@zoldri: I don't mean to hijack your thread, probably this is an easy question to ask coder777.

Also, with the calculator, do you check for division by zero?

@coder777

Would a (double) C cast to a const variable, be a compile error, meaning one would have to use const_cast? And if the variable was not a const, then one could just use (double).
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@TheIdeasMan

I'm not completely sure what you mean. See

http://www.cplusplus.com/doc/tutorial/typecasting/

You can do this without a problem:
 ``12`` ``````int x = 0; const double d = x;``````
or
 ``12`` ``````int x = 0; const double d = (double)x;``````
or
 ``12`` ``````const int x = 0; const double d = x;``````

You usually cast from more to less precision:
`long -> short // needs a cast (to make the warning go away) ` `int -> double // don't need a cast `
Ok, I have this last bit of clarification / question (I am worried because it is not my thread)

I had read the article before, but I couldn't see the difference when it is an ordinary type as opposed to base & derived classes.

 ``12`` ``````const double d=3.14159265; int i = static_cast(d); ``````

I am guessing that d remains the same, i equals 3. If not, it's compiler error, and would need a const_cast<int>?

and is this any different?

 ``12`` ``````const double d=3.14159265; int i = (int)d; ``````
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const_cast is only for pointer since it does matter if it points to a const or non value.

if const is on left of the assign operator (lvalue) it can be initialized only.

for numeric variables right of the assign operator (rvalue) it doesn't matter whether const or non const. So your examples are both ok. No difference.

For classes you should use dynamic_cast (with RTTI) since this is in fact save. It returns NULL if it's not the expected type (for pointer) or throws for references
Ok thanks coder777, I had better let the OP back to his own thread. Cheers
it didnt check for division by zero but it does now
Cool, that's a run time error fixed.
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