#include #include #include using namespace std; //The below function is used to convert char to int; int s_i(char a) { int z; switch (a) { case'0': z = 0; break; case'1': z = 1; break; case'2': z = 2; break; case'3': z = 3; break; case'4': z = 4; break; case'5': z = 5; break; case'6': z = 6; break; case'7': z = 7; break; case'8': z = 8; break; case'9': z = 9; break; } return z; } // The below function is been called from main function; // It receives two strings as a parameter from main function and stored it in string variables named "num1" & "num2"; void sum(string num1, string num2) { // Below three vectors and int variable named - "var_sum=0"are defined so that we can use it further in program; vector int_num1, int_num2, sum_result; int var_sum = 0; // In the below two for loops we will be going to convert each char of a string to int datatype and will store it in vector; // Each digit in reverse order is saved as an element in a vector; // Therefore total number of elements (you say length of vector) will be equal to the number of digits entered by the user; // Reverse order is prefered so that addition and carry handling can be done more easily; for (int i = num1.size() - 1; i >= 0; i--) { // I didn't used inbuilt function to convert a char to int; // Just above the "sum" function you can see what idea i used to convert a char to int; // the below called function "s_i(char)" will return integer value for char corresponding to it; int m = s_i(num1[i]); // There is also an other way to convert a character to integer.. /* int m = num1[i] - '0'; */ // Finally that integer is pushed back (stored from backside) into a vector; int_num1.push_back(m); } for (int i = num2.size() - 1; i >= 0; i--) { int n = s_i(num2[i]); /* int n = num2[i] - '0'; */ int_num2.push_back(n); } // As it is discussed earlier the first string passed to the function "sum(string,string)" is longer than second; // Therefore size of vector 'int_num1' should be greater than size of vector 'int_num2' // Therefore a simple Addition is performed till we have last element in vector 'int_num2' {i.e till i=num2.size() the vector int_num2 does not contain any element and it will give error; for (int i = 0; i to add '1' from 12 to '8' 8 = 8 + 12/10 = 8 + 1 = 9 => to overwrite '12' with '2' 12 = 12%10 = 2 */ // The similar logic is used in the below for loop // the only difference is that here we performed carry addition in reverse order since earlier we have also performed addition in reverse order; for (int i = 0; i= 0; i--) { cout << sum_result[i]; } } int main() { string num1, num2; // taking input from user and printing on screen; cin >> num1; cout << "You Entered : "<> num2; cout << "\nYou Entered : "<= num2.size()) { sum(num1, num2); } else { sum(num2, num1); } system("pause"); return 0; }

Long Adder (cpp)