코드업 C 언어 기초 100제 1038번 풀이 : [기초-산술연산] 정수 2개 입력받아 합 출력하기1(설명) - 머털쌤

Main ideas / lessons conveyed

• Task of the problem: Read two integers (inputs can be very large, including negative values) and print their sum.
• Important concept: The usual int type may not be sufficient because the input includes values near the bounds of integer ranges.
• Data type selection reasoning:
  • For int, the instructor notes you can only handle a limited range (mentions “last digit”/bounds informally).
  • For very large absolute values, the solution should use long long.
  • The unsigned type (unsigned int / unsigned) is not suitable because the inputs include negative numbers.
• C implementation flow:
  • Include standard header(s)
  • Define main
  • Declare two long long int variables
  • Use scanf with the correct format specifiers to read them
  • Compute and output the sum using printf
• Testing / verification:
  • The instructor describes compiling/running repeatedly to test whether:
    • values up to some boundary (including negatives) are handled correctly
    • larger maximum values also work
  • Then submit after successful tests.

Method / instruction steps (as presented)

1. Choose the correct integer type

   • Use long long int for both numbers (not int, not unsigned).

2. Write the program structure

   • #include <stdio.h>
   • int main(void) (or equivalent main signature)
   • Declare variables:
     • long long int num1;
     • long long int num2;

3. Read input with scanf

   • Use format specifiers matching long long:
     • For long long int, use %lld
   • Example pattern:
     • scanf("%lld", &num1);
     • scanf("%lld", &num2);

4. Compute and output

   • Print the sum:
     • printf("%lld", num1 + num2);

5. Testing guidance

   • Compile/run and try values including:
     • boundary-like values (including negatives)
     • then increase toward the maximum allowed input range
   • If it works through the tested boundaries, proceed to submission.

Speakers / sources featured

• Meoteol Sem (머털쌤) — the instructor narrating the solution
• CodeUp (코드업) — the problem set context (“Code Up Basic … No. 38”, problem about summing two integers)