I am writing a program to calculate sum of 2 variables. One of these is a number from 1 to 10, and the other is one letter of the alphabet (uppercase) which has value corresponding to its order. The input can be only number, only letter or both.

For instance:

Input

10  7     
C  8
E  D
9  F

Output

17
11
9
15

This is my code (This question suppose to be posted on codereview, but for some reason I can't format code right way on codereview. Please forgive me).

#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int main(){     
    char a[3], b[3];                        
    int m,n;
    //these variables hold the value of grade after converted  
                
    scanf("%s%s", a, b);

    if (a[1]!='\0')         
    {
      //this is because only number 10 has 2 digits    
        m=10;
    }
    else if (a[0]>=49 && a[0]<=57)
    {
        m=a[0]-48;      //in ascii table, 49 stands of 1 and 57 stands for 9
    }
    else
    {
        m=a[0]-64;      //in ascii table, 65 stands for 'A'
    }

    if (b[1]!='\0')              
    {
        n=10;
    }
    else if (b[0]>=49 && b[0]<=57)      
    {
        n=b[0]-48;
    }
    else         
    {
        n=b[0]-64;
    }

    printf("%d", m n);
    return 0;
}

It works but I think it is a little bit complicated. So I want to ask if there is any way to optimize the detection.

And how to deal with large input number.

Any help would be appreciated.

CodePudding user response：

You can use stroll function to convert string to long long. It looks much cleaner, and this program can deal from -9223372036854775808 to 9223372036854775807 as output.

#include <stdio.h>
#include <stdlib.h>

int main(void) {

  char string_num1[20], string_num2[20];
  scanf("%s%s", string_num1, string_num2);
  long long num1 = strtoll(string_num1, NULL, 10);
  long long num2 = strtoll(string_num2, NULL, 10);
  long long num3 = num1   num2;

  printf("%lld", num3);

  return 0;
}