Thread: Help an ambitious 16 year old learn C

This is great that you guys are talking about standards, but you all are ignoring a couple key things here: which I have now bolded in my original post. Please re-read.

Originally Posted by Xlayer

I finally figured out how to use Codeform. I had to use the online version though. Here is my code for the Fibonacci Number Program.

I used this website to figure out what a Fibonacci Number was:
http://www.jimloy.com/algebra/fibo.htm

It works all the way up to Line 47 which gives me a negative value:
Picture of Output

Code:

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

int main()
{
    int n; /* Number of Fibonnacci Numbers to Find (Inputed by User) */
    int index = 1; /* Index of Fibonnaci Number (Starts with 1) */
    long int fib_num = 0; /* Fibonacci Number */
    long int num1 = 1; /* Represents 1 Fib# before Last Fib# */
    long int num2 = 1; /* Reprsents Last Fib# */

    /* Prompts user for n, and reads input */
	printf( "Please enter the amount of Fibonacci\n"
	"numbers to find: ");
	scanf( "%ld", &n );

    /* Executed until Fib#'s Found == Fib#'s Wanted by User */
	while ( index <= n )
	{
	    if ( index <= 2 )
	    {
	        printf( "\nFibonacci Number #%d = %ld", index, num2 );
	    }
	    else
	    {
            fib_num = num1 + num2;
            num1 = num2;
            num2 = fib_num;
            printf( "\nFibonacci Number #%d = %ld", index, num2);
	    }
	    index++;
	}
	return 0;

}

I completely ignored pointers, and I am sure there is probably a better algorithm. Let the corrections/learning begin.

(I don't see a use for pointers even though I am sure there is one, but in this situation it seems that the variables are used until the program terminates so i can't see how you could free the memory much sooner than it already is.)

I started my Calculator program. It compiles fine, but when it reaches "Enter a Math Operator: " it doesn't wait for the user to input an operator. Instead, it automatically skips to "Enter Your Second Number: " and waits there for input.

This is shown in this picture of the output:
Picture of Error

Here is my code:

Code:

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

int main()
{
	float num1;
	float num2;
	float answer;
	char math_operator;
	char enter;

	printf(
	" ---------------------------------------------------------\n"
	"                Math Calculator\n"
	" ---------------------------------------------------------\n\n"
	" This is program is only intended for Math Operations\n"
	" that only require 3 arguments, which in this case is\n"
	" 2 numbers and a desired Math Operator. The operations\n"
	" which can be performed by this program are explained in\n"
	" the explantion of available Math Operators located below.\n\n\n"
	" --| Explanation of Math Operators |---------------------|\n"
	"   |                                                     |\n"
	" + | This operator returns the result of one             |\n"
	"   | number added to another number.                     |\n"
	"   |                                                     |\n"
	" - | This operator returns the result of one             |\n"
	"   | number subtracted from another number.              |\n"
	"   |                                                     |\n"
	" / | This operator returns the result of one             |\n"
	"   | number divided by another number.                   |\n"
	"   |                                                     |\n"
	" * | This operator returns the result of one             |\n"
	"   | number multiplied by another number.                |\n"
	"   |                                                     |\n"
	" ^ | This operator returns the result of the             |\n"
	"   | first number inputed, raised to the power           |\n"
	"   | of the second number.                               |\n"
	"   |                                                     |\n"
	" ! | This operator returns the result of square          |\n"
	"   | root of the first number, given the index,          |\n"
	"   | which is the second number inputed. Use 2           |\n"
	"   | as the value of the second number for a             |\n"
	"   | regular square root operation.                      |\n"
	" --|-----------------------------------------------------|\n\n"
	" Press ENTER to begin calculations.\n\n" );

	scanf( "&#37;c", &enter );

	if( enter == '\n' )
	{
	    printf( " Please Enter Your First Number: " );
	    scanf( "%f", &num1 );
	}

    printf( "\n  Please Enter a Math Operator: " );
    scanf( "%c", &math_operator );

    printf( "\n Please Enter Your Second Number: " );
    scanf( "%f", &num2 );

	if( math_operator == '+' )
	{
	    answer = num1 + num2;
	}

	if( math_operator == '-' )
	{
	    answer = num1 - num2;
	}

	if( math_operator == '/' )
	{
	    answer = num1 / num2;
	}

	if( math_operator == '*' )
	{
	    answer = num1 * num2;
	}

	if( math_operator == '^' )
	{
	    answer = pow( num1, num2 );
	}

	if( math_operator == '!' )
	{
	    answer = pow( num1, ( 1 / num2 ) );
	}

	printf( "%f %c %f = %f", num1, math_operator, num2, answer );
	
	return 0;
}

Let the corrections/learning begin.

Also, now that I think about it. Would it be at all useful to use a pointer for the variable "enter" since it does not need to be used throughout the rest of the program?