Need Help Converting Binary to Decimal in C

[Solace_]

In a nutshell I have a school project that wants me to convert an entered binary number to a decimal.

 

Program should go something like this:

User enters binary number -> binary number is converted one digit at a time -> decimal number is displayed.

 

I am very new to C and programming in general. If you have any tips or snippets of code you could share that would be great.

 

Thanks very much!

[straight_stewie]

33 minutes ago, Solace_ said:

In a nutshell I have a school project that wants me to convert an entered binary number to a decimal.

Do you know how to read binary by hand?

[Solace_]

4 minutes ago, straight_stewie said:

Do you know how to read binary by hand?

yes I do

[straight_stewie]

10 minutes ago, Solace_ said:

yes I do

Great! This is actually a pretty simple thing to do.

Here's the algorithm:

1. get the users input
2. initialize an integer to 0
3. Put the users input into a char array
4. Reverse the char array
5. Iterate through the char array from smallest index to largest doing steps 6 and 7
6. If the current char in the array is character '1', then the integer is equal to itself plus 2 to the power of the current index of the array (integer += 2^index)
7. If the current char in the array is character '0', do nothing
8. Output the integer.

Can you post your code when you're done?

[Solace_]

8 minutes ago, straight_stewie said:

Great! This is actually a pretty simple thing to do.

Here's the algorithm:

1. get the users input
2. initialize an integer to 0
3. Put the users input into a char array
4. Reverse the char array
5. Iterate through the char array from smallest index to largest doing steps 6 and 7
6. If the current char in the array is character '1', then the integer is equal to itself plus 2 to the power of the current index of the array (integer += 2^index)
7. If the current char in the array is character '0', do nothing
8. Output the integer.

Can you post your code when you're done?

thanks very much, I will certainly try and remember to.

[Remixt]

50 minutes ago, Solace_ said:

In a nutshell I have a school project that wants me to convert an entered binary number to a decimal.

 

Program should go something like this:

User enters binary number -> binary number is converted one digit at a time -> decimal number is displayed.

 

I am very new to C and programming in general. If you have any tips or snippets of code you could share that would be great.

 

Thanks very much!

int getDecimal (int binary){
	if (binary == 0){
		return 0;
	}
	int decimal = 0; // keep track of the total
	int j = floor(log10(abs(binary))) + 1; // returns how many digits are in the binary number
	int i = 0; // using i to iterate through each digit in the for loop.
	
	for int (; i < j; i++){ //starting with the left most digit start adding up the value for each position.
	
			decimal+= binary[i]^j/2; // Adds the decimal value of the binary position to the end result.
			
			j--; // takes j to the next digit so it can take the correct power.
		
	}
	return decimal;
}

I didn't test this, but it should work I think.

[OhadShwartzman]

The way I like to do it is read one digit at a time from right to left, and do 2^pos*digit and then add al of them up

[Unimportant]

Implementation of @straight_stewie 's algorithm (sort of)

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

int main(void)
{
	//Maximum amount of bits user can enter. +1 because '\n' gets recorded.
	const int  MAXBITS = (sizeof(unsigned int) * 8) + 1;	

	//Get binary number from user into InBuffer.
	char InBuffer[MAXBITS];		
	printf("Enter binary number: \n");
	fgets(InBuffer, MAXBITS, stdin);
	int Length = strlen(InBuffer) - 1; //-1 because '\n' gets recorded.

	//Loop trough each character in the input string.
	unsigned int Result = 0;
	for (int i = 0; i < Length; i++)
	{
		//Check for invalid characters.
		if (InBuffer[i] > '1' || InBuffer[i] < '0')
		{
			printf("Invalid binary number entered!\n");
			return 1;
		}

		//Multiply each char with it's bitvalue and add to result.
		Result += (InBuffer[i] - '0') * (1 << (Length - i - 1));
	}
	
	printf("Result: %d\n", Result);

	return 0;
}