Member Avatar for egolovin

can someone look at this? in theory it should work but i cant figure it out
thanks in advance

#include<iostream>
#include<string>
#include<cmath>
using namespace std;
void binToDec(string getBinary);
int main()
{
	string getBinary;
	cout<<"Enter a Binary Number:"<<endl;
	cin>>getBinary;
	binToDec(getBinary);
	
return 0;
}
void binToDec(string getBinary)
{
	int setLength,total=0;
	double placeholder=0;
	setLength=getBinary.size();
	
	for(int i=setLength;i>0;i--)
	{
		int num=pow(2.0,placeholder);
		int test=getBinary[i];
		if (test==1)
		{
			total=total+num;
		}

		placeholder=placeholder +1;
	
	}
	cout<<total<<endl;


}
  • 3 Contributors
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  • Latest Post Latest Post by egolovin

Dani AI

Generated

A few focused notes that address the actual faults in ’s snippet and build on the replies from and .

The direct bugs: the loop uses an index that runs past the end of the string (accessing index setLength is out of range), characters are examined as their raw ASCII values, and pow with doubles is unnecessary (and can introduce rounding). Those three together explain wrong answers or crashes.

A simple, robust approach is Horner’s rule: scan the string left-to-right, validate each char, then update an integer accumulator by multiplying by 2 and adding the digit. This avoids pow, avoids floating arithmetic, and runs in O(n) time with O(1) extra memory:

unsigned long long total = 0;
for (size_t i = 0; i < getBinary.size(); ++i) {
    char c = getBinary[i];
    if (c != '0' && c != '1') {
        // handle invalid input
        break;
    }
    total = total * 2 + (c - '0');
}
std::cout << total << '\n';

Practical extras: trim whitespace or reject an empty string, check for overflow (if the string length exceeds the target type’s bits or test before multiplying), and report invalid characters instead of silently skipping them. If library helpers are allowed, std::stoul(getBinary, nullptr, 2) or std::bitset<N> are convenient alternatives for standard parsing and fixed-width conversions.

Tie-back: ’s point about integer arithmetic is correct for efficiency, and ’s reminder about character vs numeric comparison is on target — combine those observations and fix the indexing and the pow usage, and the conversion will be correct and reliable.

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Member Avatar for rhoit

I guess using string is not the good idea.
What we use to do was.... some how take the binary in the int or long.

then take a loop and extract the element one by one form the last...

I guess this is the efficient method.. some how you are wasting too much memory space using string.

int dec;
int bin;
cin>>bin;

for(int i=0; bin!=0; bin/=10)
  dec+=bin%10*pow(2, i++);
Member Avatar for egolovin

oh sorry i forgot to add i have to use string as binary this is hw for school. pow only works with double. :(

Member Avatar for rhoit

oh sorry i forgot to add i have to use string as binary this is hw for school. pow only works with double. :(

if you are such crazy about the string.
then you must subtract 48 from the each character of the string

as ASCII value of 1 is 49
when you subtract 49-48 = 1
then you can use it as normally

Member Avatar for dougy83

What

can someone look at this? in theory it should work but i cant figure it out
thanks in advance

if (test==1)

That line should be if (test == '1') 1 is different to '1' (character code 49, as Rhohitman said). Also, for powers of 2 you don't have to use pow(). Using the shift operator<< works fine for integers. So pow(2., x) can be replaced with 1<<x

Member Avatar for egolovin

Thanks alot :d

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