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#include <stdio.h>
#include <string.h>
#include <math.h>
unsigned long long int bin2dec(const char *string, const size_t size)
{
unsigned long long int value = 0;
for(size_t index=0;index<size;index++)
{
// moving from the end to the beginning, get a character from the string
// and convert it from a character containing a digit to a number
short bit = string[size-index-1]-'0';
// in the original question this was: value += bit*pow(2,index);
// but we can just do this and get the same effect
// without multiplication or library function
value += bit<<index;
}
return value;
}
int main()
{
const char * binary = "111111111111111111111111111111";
unsigned long long int decimal = bin2dec(binary, strlen(binary));
printf("%llu\n",decimal);
return 0;
}
