initial commit

1 files changed, 197 insertions, 0 deletions

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..766bd88
--- /dev/null
+++ b/main.c
@@ -0,0 +1,197 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DEFAULT_SIZE 40 //default size out output binary string
+
+//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;
+}
+
+//itoh(): Converts integer to hexadecimal with the division algorithm and shows working. Requires length of result string.
+void itoh(char s[], char *result, 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
+
+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
+unsigned long long integer = 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'){integer += ((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 (integer)
+	{
+	switch (integer % 16)
+		{
+		case 0:
+			result[i] = '0';
+			break;
+		case 1:
+			result[i] = '1';
+			break;
+		case 2:
+			result[i] = '2';
+			break;
+		case 3:
+			result[i] = '3';
+			break;
+		case 4:
+			result[i] = '4';
+			break;
+		case 5:
+			result[i] = '5';
+			break;
+		case 6:
+			result[i] = '6';
+			break;
+		case 7:
+			result[i] = '7';
+			break;
+		case 8:
+			result[i] = '8';
+			break;
+		case 9:
+			result[i] = '9';
+			break;
+		case 10:
+			result[i] = 'A';
+			break;
+		case 11:
+			result[i] = 'B';
+			break;
+		case 12:
+			result[i] = 'C';
+			break;
+		case 13:
+			result[i] = 'D';
+			break;
+		case 14:
+			result[i] = 'E';
+			break;
+		case 15:
+			result[i] = 'F';
+			break;
+		default:
+			printf("What just occured is meant to be impossible to happen...\n"); exit(1);
+			break;
+		}
+
+	printf("%llu\t| %c\n", integer, result[i]);
+
+	integer /= 16;
+
+	++i;
+	if (i > length-1)
+		{
+		result[0] = 'E'; result[1] = '\0';
+		return;
+		}
+	}
+result[i] = '\0';//terminate result with null char
+
+char c;
+int j = i-1;//i-1 is the first character at the end of the string
+
+//the string needs to be reversed, for the result to be correct.
+
+for(i=0; i < j; ++i, --j)
+	{
+	c = result[j];
+	result[j] = result[i];
+	result[i] = c;
+	}
+
+}
+
+int main(int argc, char *argv[])
+{
+char input[DEFAULT_SIZE];//input string is DEFAULT_SIZE in length
+
+//result string
+char *result = malloc(DEFAULT_SIZE*sizeof(char));
+if (!result){printf("Malloc failed!\n"); return 1;}
+result[DEFAULT_SIZE-1]='\0';//add null terminating char
+
+if (!argv[1]){goto stdinMode;}
+
+	if (argv[1][1] == '-')
+		{
+		printf("Usage (stdin mode): %s\n", argv[0]);
+		printf("Ctrl+D to exit\n");
+		printf("Usage (cli args mode): %s [decnum]\n", argv[0]);
+		printf("Converts decimal number to hex via the division algorithm.\n");
+		printf("Licence: GPLv3\n");
+		return 0;
+		}
+
+
+	//strip out invalid chars from the input string
+	int a,q;//counter variables
+	for (a=0; argv[1][a] != '\0'; ++a)
+	        {
+	        if ((argv[1][a] < '0')||(argv[1][a] > '9'))//if argv[1][i] is a character to remove....
+	                {
+			q=a;
+			while(argv[1][q] != '\0'){argv[1][q++] = argv[1][q+1];}//shift all characters above left, overwriting the character
+			--a;//deincrement a, since the string was just shrunk by one and the one just above could indeed be a matching char
+			}
+			}
+
+
+
+	itoh(argv[1], result, DEFAULT_SIZE-1);
+	printf("0x%s\n",result);
+
+	free(result);
+	return 0;
+
+stdinMode: ;
+int i;
+nextnum: i=0;
+char *character = fgets(input, DEFAULT_SIZE, stdin);
+if (!character){free(result); 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
+                }
+        }
+
+itoh(input, result, DEFAULT_SIZE-1);
+printf("Result: 0x%s\n", result);
+
+goto nextnum;
+
+//this wont be reached, but included anyway in case the above goto is removed
+free(result);
+
+return 0;
+}
+