Create toDecimal.c

Conversions/toDecimal.c

@@ -0,0 +1,38 @@
+/*
+ * convert from any base to decimal
+ */
+
+#include <stdio.h>
+#include <ctype.h>
+
+int main(void) {
+	int base, i, j;
+	char number[100];
+	unsigned long decimal = 0;
+	
+	printf("Enter the base: ");
+	scanf("%d", &base);
+	printf("Enter the number: ");
+	scanf("%s", &number[0]);
+	
+	for (i = 0; number[i] != '\0'; i++) {
+		if (isdigit(number[i]))
+			number[i] -= '0';
+		else if (isupper(number[i]))
+			number[i] -= 'A' - 10;
+		else if (islower(number[i]))
+			number[i] -= 'a' - 10;
+		else
+			number[i] = base + 1;
+		
+		if (number[i] > base)
+			printf("invalid number\n");
+	}
+	
+	for (j = 0; j < i; j++) {
+		decimal *= base;
+		decimal += number[j];
+	}
+	
+	printf("%lu\n", decimal);
+}