initial commit

1 files changed, 122 insertions, 0 deletions

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..78fd778
--- /dev/null
+++ b/main.c
@@ -0,0 +1,122 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "primes.h"
+#define DEFAULT_SIZE 40
+
+//printf colour definitions
+#define KGREEN  "\x1B[32m"
+#define KRESET  "\x1B[0m"
+
+
+
+//powq(): power
+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 primeDec(char s[], int length)
+{
+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
+	}
+
+i=0;
+while(1)
+	{
+	if ((input % primes[i]) != 0)
+		{
+		printf("%ld / %d = %lf\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 %s(works)%s\n", input, primes[i], input/primes[i], KGREEN, KRESET);
+		input = input/primes[i];//input is now the new number
+
+		//check if prime (linear search shouldn't take too long)
+		int j = 0;
+		for (; j < 998; ++j)
+			{
+//			if (primes[j] > input){printf("%s (works)%s", KGREEN, KRESET); break;}
+			if (primes[j] > input){break;}
+
+			else if (primes[j] == input)
+				{
+				printf("%sWe're done.%s Times those divisions (times by each divisor on the (works) lines, then the divisor on the last line, then the last prime).\n", KGREEN, KRESET);
+				return;//the number was determined to be prime, so complete
+				}
+			}
+		if (j > 998){printf("Out of primes. Good job\n"); exit(1);}
+		}
+
+	}
+
+}
+
+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("Shows working of prime decomposition, you gotta extract the answer yourself though.\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
+                }
+        }
+
+primeDec(input, DEFAULT_SIZE-1);
+
+goto nextnum;
+
+return 0;
+}
+