C - Adding the numbers in 2 strings together if a different length

Question

If I had two strings:

a = \"1234\"
b = \"4321\"

I could add the two numbers together like this:

for(i=0; i

        

Answer 1

int num(char x,int len){
    if(len <0)
        return 0;
    return ((x=='1') ? 1 :  (x=='2') ? 2 : (x=='3') ? 3 : (x=='4') ? 4 : (x=='5') ? 5 : (x=='6') ? 6 : (x=='7') ? 7 : (x=='8') ? 8 : 9);
}

int main(){


    int result[100];
    int i=0;
    char num1[] = "123456789123456789";
    char num2[] = "1234567811111111111111111111";
    int carry = 0;
    int l1= strlen(num1)-1;
    int l2 = strlen(num2)-1;
    int result1;


    while(1){
        if(l1 < 0  && l2 <0 && carry == 0)
            break;
        result1 = num(num1[l1],l1) + num(num2[l2],l2);
        l1--;
        l2--;
        if(carry>0){
            result1 +=carry;
            carry = 0;
        }
        carry = result1 / 10;
        result[i] = (result1 % 10);
        i++;
    }

    i--;
    printf("\n");

    while(i>=0){
            printf("%d",result[i]);
            i--;
    }

}