Question

Hi, I was wondering if you'd be able to help me figure out how to evaluate the sum of the numbers in char data type since built in data type is not applicable (cannot contain 80 digits).(C programming).(the problem is written below). Is it necessary to use multidimensional array ?

A country has a budget of more than 81 trillion yen. We want to process such data, but conventional integer type which uses signed 32 bit can represent up to 2,147,483,647.

Your task is to write a program which reads two integers (more than or equal to zero), and prints a sum of these integers.

If given integers or the sum have more than 80 digits, print "overflow".

Input

Input consists of several datasets. In the first line, the number of datasets N (1 ≤ N ≤ 50) is given. Each dataset consists of 2 lines:

The first integer
The second integer

The integer has at most 100 digits.

Output

For each dataset, print the sum of given integers in a line.

Sample Input

6
1000
800
9999999999999999999999999999999999999999
1
99999999999999999999999999999999999999999999999999999999999999999999999999999999
1
99999999999999999999999999999999999999999999999999999999999999999999999999999999
0
100000000000000000000000000000000000000000000000000000000000000000000000000000000
1
100000000000000000000000000000000000000000000000000000000000000000000000000000000
100000000000000000000000000000000000000000000000000000000000000000000000000000000

Output for the Sample Input

1800
10000000000000000000000000000000000000000
overflow
99999999999999999999999999999999999999999999999999999999999999999999999999999999
overflow
overflow

Answer 1

Given below is the code for your question. Please do rate the answer if it helped. Thank you.

#include <stdio.h>
#include <string.h>
//adds num1 and num2 and stores result in ans. right most digit is stored in index 0 for all numbers
//returns 0 if overflow and 1 if no overflow

int add(char num1[], char num2[], char ans[]);
void print(char num[]); //displays the number, right most digit is in index 0
void reverse(char s[]); //reverses a string
int main(){
int numTests;
char num1[101], num2[101], ans[101];

printf("Enter number of tests followed by 2 numbers for each test case\n");
scanf("%d", &numTests);

for(int i = 0; i < numTests; i++){
scanf("%s %s", num1, num2);
reverse(num1);
reverse(num2);
if(add(num1, num2, ans))
print(ans);
else
printf("overflow\n");
}
return 0;
}

int add(char num1[], char num2[], char ans[])
{
int d1, d2, sum , carry = 0;
int len1 = strlen(num1), len2 = strlen(num2);
int i = 0, j = 0, k = 0;

if(len1 > 80 || len2 > 80)
return 0; //overflow

while(i < len1 || j < len2){
if(i < len1 )
d1 = num1[i++] - '0'; //get the numeric equivalent of the char
else
d1 = 0;
  
if(j < len2)
d2 = num2[j++] - '0';
else
d2 = 0;

sum = carry + d1 + d2;

if(sum > 9){
sum -= 10;
carry = 1;
}
else
carry = 0;
//printf("d1 = %d, d2 = %d, s = %d,c = %d\n", d1, d2, sum, carry);
ans[k++] = sum + '0'; //store the digit as char
}

if(carry && k >= 80)
return 0; //overflow
else{
if(carry)
ans[k++] = '1';
ans[k] = '\0';
return 1;
}
}

void print(char num[]) //displays the number, right most digit is in index 0
{
int len = strlen(num);
for(int i = len-1; i>= 0; i--)
printf("%c", num[i]);
  
printf("\n");
}

void reverse(char s[]){
int len = strlen(s);
int i = 0, j = len-1;
char temp;
while(i < j){
temp = s[i];
s[i] = s[j];
s[j] = temp;
i++;
j--;
}
}

output
----
Enter number of tests followed by 2 numbers for each test case
6
1000
800
1800
9999999999999999999999999999999999999999
1
10000000000000000000000000000000000000000
99999999999999999999999999999999999999999999999999999999999999999999999999999999
1
overflow
99999999999999999999999999999999999999999999999999999999999999999999999999999999
0
99999999999999999999999999999999999999999999999999999999999999999999999999999999
100000000000000000000000000000000000000000000000000000000000000000000000000000000
1
overflow
100000000000000000000000000000000000000000000000000000000000000000000000000000000
100000000000000000000000000000000000000000000000000000000000000000000000000000000
overflow