I've been trying to build a calculator that gets around the limitations of int variables by splitting the number into smaller chunks. I've gotten the add to work successfully but have not been able to get the multiply logic to follow the same path. It works up to a certain point, but the logic fails when I enter a larger number. For example, entering 80 *120 returns 9600. If I enter a number like 222 * 444, it comes up with is -504. I'm not quite sure how to fix this. Im still pretty weak on vector array's.
Code:/*********************************** * Pre-Compiler Directives * ***********************************/ #include <iostream> // cin, cout, >>, << #include <iomanip> // setfill() #include <vector> // vector<T> #include <algorithm> // sort() using namespace std; /*********************************** * Global Variables * ***********************************/ typedef vector<short int> BigInt; // short int = type BigInt = what we call the vector BigInt int1; BigInt int2; BigInt answer; BigInt x; /*********************************** * Function Definitions * ***********************************/ void readBig(BigInt & x); void printBig(const BigInt & x); void add(BigInt int1, BigInt int2, BigInt & answer); void multiply(BigInt int1, BigInt int2, BigInt & answer); /*********************************** * Main * ***********************************/ int main() { cout << "Enter BigInts in blocks of 3 digits (-1 to stop).\n"; char option; for (;;) { cout << "\nEnter +, -, *, /, or Q (to quit): "; cin >> option; if (option == 'Q' || option == 'q') break; BigInt int1, int2, answer; cout << "Enter first BigInt: "; readBig(int1); cout << "Enter second BigInt: "; readBig(int2); switch (option) { case '+' : add(int1, int2, answer); break; case '*' : multiply(int1, int2, answer); break; default : cerr << "Illegal operation\n"; } // cout << "\n" << int1[1]; Accesses the first integer cout << "Answer: "; printBig(answer); } } /******************************************** * readBig reads a BigInt. * * * * Receive: BigInt x * * Pass back: x with a value input for it * ********************************************/ void readBig(BigInt & x) { short int block; for (;;) { cin >> block; if (block < 0) return; x.push_back(block); } } /******************************************** * printBig displays a BigInt. * * * * Receive: BigInt x * * Output: x * ********************************************/ void printBig(const BigInt & x) { cout << setfill('0'); for (int i = 0; i < x.size(); i++) { cout << setw(3) << x[i] << ' '; if (i > 0 && i % 20 == 0) cout << endl; } cout << endl; } /******************************************************* * 'add' adds two BigInts. * * Receive: BigInts int1 and int2 * * Pass back : int1 + int2 * * * *******************************************************/ void add(BigInt int1, BigInt int2, BigInt & answer) // cout << "\n" << int1[1]; Accesses the first integer second element { short int first, // a block of int1 second, // a block of int2 result, // a block in their sum carry = 0; // the carry in adding two blocks int size1 = int1.size(), size2 = int2.size(), maxSize = (size1 < size2 ? size2 : size1); reverse(int1.begin(), int1.end()); reverse(int2.begin(), int2.end()); for (int i = 0; i < maxSize; i++) { if (i < size1) first = int1[i]; else first = 0; if (i < size2) second = int2[i]; else second = 0; short int temp = first + second + carry; cout << temp << endl; // For logic debugging result = temp % 1000; carry = temp / 1000; answer.push_back(result); } if (carry > 0) answer.push_back(carry); reverse(answer.begin(), answer.end()); } void multiply(BigInt int1, BigInt int2, BigInt & answer) { short int first, // a block of int1 second, // a block of int2 result, // a block in their sum carry = 0; // the carry in multiplying two blocks int size1 = int1.size(), size2 = int2.size(), maxSize = (size1 < size2 ? size2 : size1); reverse(int1.begin(), int1.end()); reverse(int2.begin(), int2.end()); for (int i = 0; i < maxSize; i++) { if (i < size1) first = int1[i]; else first = 0; if (i < size2) second = int2[i]; else second = 0; short int temp = (first * second) + carry; cout << temp << endl; // For logic debugging result = temp % 1000; carry = temp / 1000; answer.push_back(result); } if (carry > 0) answer.push_back(carry); reverse(answer.begin(), answer.end()); }
Originally Posted by twomers
