How to COPY or CREATE a DISSASSEMBLY of an executable file or a C source code? [duplicate]

I got an assignment from my college to create this

Now I know there might be some way, that I can copy the disassembly of my C code I created from a debugger, I guess...

If there is a way please let me know... Or atleast...

Help me with the disassembly of this code I created...

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

//Logic loop
int to_base3(int decimal_number) 
{
    //To return the function at the end of recursion 
    if (decimal_number == 0)  
        return 0;
    //The Recursion  
    else
        return (decimal_number % 3 + 10 *  to_base3(decimal_number / 3)); 
} 

//Main function  
int main() 
{ 
    int decimal_number;
    char check[20];
    //Inputting the values and checking for characters
    do{                             
        int flag=1;
        printf("Enter the number: ");
        fgets(check, 19, stdin);
        //Loop to check for number or character
        for(int i=0; i<sizeof(check);i++){
            if(isdigit(check[i])){
                flag =0;
                break;
            }
            else{
                continue;
            }
        }
        //The place where to_base3() gets called
        if(flag==0)
        {
            decimal_number = atoi(check);
            printf("Base 3 number: %d\n", to_base3(decimal_number));
        }
        //If flag == 1 i.e. if it's a char, then exit the loop
        else
            break;
    }while(1);
    //The final statement
    printf("Thank you for using my program. Bye!");
    return 0;
} 

Also, if you think that you can come up a shorter assembly code for this problem... Let me know...