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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "primes.h"
#define DEFAULT_SIZE 30
//powq(): square roots
unsigned long long powq(int number, int power)
{
unsigned long long result = 1;//result int, 1 by default
if (!power){return 1;}//if to the power of 0, return 1
while(power)//loop until all powers have been calculated
{
result *= number;//in the end result=number*number*number*etc until power is reached
--power;//--power since a power has been calculated
}
return result;
}
void checkPrime(char s[], int length)
{
//if (s[0] == '\0'){result[0] = 'E'; result[1] = '\0'; return;}//catch case of blank input
//if (s[0] == '0' && s[1] == '\0'){printf("0\t| 0\n"); result[0] = '0'; result[1] = '\0'; return;}//catch case of 0 input
if (s[0] == '\0'){printf("Error\n"); return;}//catch case of blank input
if (s[0] == '0' && s[1] == '\0'){printf("Error\n"); return;}//catch case of 0 input
if (s[0] == '1' && s[1] == '\0'){printf("We all know that 1 isn't a prime number\n"); return;}//catch case of 1 input
int power = 0; //int to store the power.
while(s[power] != '\0'){++power;}//increment power for however many non-null chars in the string.
--power;//The correct power is actually one less than above returns
int i = 0;//counter int
long input = 0;//where the converted int is stored
while (s[i] != '\0')//convert the string of decimal numbers into a long long int
{
if (s[i] >= '0' && s[i] <= '9'){input += ((s[i] - '0') * powq(10,power));}//integer = integer + ([char converted to number] * (10^[position of number in string]))
++i;
--power;//Deincrement the power. E.g. ([charvalue]*(10^3))+([nextcharvalue]*(10^2)) etc
}
double squareRoot = sqrt((double)input);
printf("Square root: %lf\n", squareRoot);
i=0;
while(1)
{
if (primes[i] > (int)squareRoot){printf("%d is larger than %lf. Prime\n", primes[i], squareRoot); return;}//if the prime is larger than the integer part of the sqaure root, it is not a prime
if ((input % primes[i]) != 0)
{
printf("%ld / %d = %lf not round\n", input, primes[i], (double)input/primes[i]);
if (i > 998){printf("Out of primes. Good job\n"); exit(1);}
++i;//move up to next prime
}
else
{
printf("%ld / %d = %ld round\n", input, primes[i], input/primes[i]);
printf("Round result, number is not prime\n");
break;
}
}
}
int main(int argc, char *argv[])
{
char input[DEFAULT_SIZE];//input string is DEFAULT_SIZE in length
if (!argv[1]){goto stdinMode;}
if (argv[1])
{
printf("Usage (stdin mode): %s\n", argv[0]);
printf("Ctrl+D to exit\n");
printf("Determines if number is prime and shows working.\n");
printf("Licence: GPLv3\n");
return 0;
}
stdinMode: ;
int i;
nextnum: i=0;
char *character = fgets(input, DEFAULT_SIZE, stdin);
if (!character){exit(0);}//exit if EOF (fgets() returns -1 on EOF or error)
character = strstr(input,"\n");//try to find the newline in the input so it can be overwritten
if (!character){printf("Input too long\n"); while(getchar() != '\n'); goto nextnum;}//if more than 40 chars were read, input was too long
character = '\0'; //overwrite newline with null char
//strip out invalid chars from the input string
int j;//another counter variable
for (i=0; input[i] != '\0'; ++i)
{
if ((input[i] < '0')||(input[i] > '9'))//if input[i] is an invalid character
{
j=i;
while(input[j] != '\0'){input[j++] = input[j+1];}//shift all characters above left, overwriting the character
--i;//deincrement i, since the string was just shrunk by one and the one just above could indeed be a matching char
}
}
checkPrime(input, DEFAULT_SIZE-1);
goto nextnum;
return 0;
}
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