Generic function for convert any number system to decimal number in C language

Hi

Check the following link, Clearly explained.


Conversion of numbers from one to another number system[^]

Regards,
Venkatesh.

There is nothing "generic" in such function, or, in a way, the only one function is "generic enough". Here is one possible signature of such function:

char* Convert(int inputBase, int OutputBase, char* input);

or, more correct in C way, to avoid the problem of string deallocation:

void Convert(int inputBase, int OutputBase, char* input, char* output);

In the second case, the called should supply both char pointers preserving sufficient room for output value.

This is so because (please see my comment to the question), the notion of the base is only applicable to strings representing numbers, not the numbers (you can think of numbers as always binary). You just need to make a string based on input string. The body of this function is your home exercise. :-)

—SA

Here's how I would proceed with this homework assignment;

Write a routine to convert from (say) base 4 to base 8 (choose any two)

Now write another to convert from base 4 to base 16

Keep picking pairs of numbers and writing the routines to convert between them.

Once you have done it a few times, you will find yourself writing lots of code again and again - indeed you can cut and paste much of it.

Now, start thinking about how to make it more generic - instead of hard-coding any numbers, have them as parameters to the method.

when you get that far, if you have specific issues, please don't hesitate to ask again for help.

#include<stdio.h>
#include<string.h>
#include<ctype.h>
#include<malloc.h>
#include<conio.h>
#include<stdlib.h>
#include<math.h>

int numInDec(char *numStr,int base)
{
	int number;
	int ch;
	char sh[100];
	int i=0,j=0;
 
	printf("input No in Hex: ");
	//scanf("%s",&sh);
	strcpy(sh,numStr);
	number = 0;
	i =strlen(sh);
	j=0;
	while(i!=0)
	{
		ch = sh[j];
		ch = toupper(ch); 
		printf("Ch:%d\t%d\t%d\n",ch,'7',ch-'7');
 
		if(('0' <= ch && ch <= '9'))
		{
			number = number * base;
			printf("Number :%d\n",number);
			number = number + (ch - '0');
		}
 
		if(('A' <= ch && ch && ch <= 'Z'))
		{
			number = number * base;
			printf("Number :%d\n",number);
			number = number + (ch - '7');
		}
 
		printf("Number :%d\n",number);
		i--;
		j++;
 
	}
 
	printf("The O/p No in Decimal is : %d\n",number);
	return number;
}
 
int main()
{
   int n1=0,n2=0,n3=0,n4=0;
   n1 = numInDec("1430",5);
   n1 = numInDec("110",2);
   n1 = numInDec("2A",12);
   n1 = numInDec("10",10);
   printf("\n%d %d %d %d\n",n1,n2,n3,n4);
   return 0;
}

Here is my solution, i just pass number as a string and its base as a integer.
NOTE This code required error handling