There's probably some extra checking to do on the flip side for numbers that are not the exact same length

Co-authored-by: sigonasr2 <sigonasr2@gmail.com>

src/main.c

@@ -2,26 +2,12 @@
 #include "utils.h"
 
 /*
-    215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.
-
-    What is the sum of the digits of the number 21000?
-
+    
 
-    https://projecteuler.net/problem=16
+    https://projecteuler.net/problem=
 */
 
 int main(int argc,char**argv) {
     
-    int i=1;
-    struct String numb = {1,"2"};
-    while (i++<1000) {
-        numb = add(numb,numb);
-    }
-    //printf("%s",numb.str);
-    int sum=0;
-    for (int j=0;j<numb.length;j++) {
-        sum+=numb.str[j]-'0';
-    }
-    printf("The sum of the digits of %s is %d",numb.str,sum);
     return 0;
 }

src/utils.c

@@ -23,7 +23,21 @@ struct String add(struct String numb1, struct String numb2){
             }
         }
     } else {
-
+        for (int offset=0;offset<numb1.length;offset++) {
+            str = realloc(str,++digitCount);
+            //printf("Digit count is now %d\n",digitCount);
+            if (numb1.length>offset) {
+                //printf("%c %c\n",numb1.str[numb1.length-offset-1],numb2.str[numb2.length-offset-1]);
+                int sum=((numb1.str[numb1.length-offset-1]-'0')+(numb2.str[numb2.length-offset-1]-'0'))+((carryover>0)?carryover--:0);
+                if (sum>=10) {
+                    carryover=1;
+                    sum-=10;
+                }
+                str[offset]=sum+'0';
+            } else {
+                str[offset]=numb2.str[numb2.length-offset-1];
+            }
+        }
     }
     if (carryover>0) {
         str = realloc(str,++digitCount);