#include
	#include
	/*
	* The isnumber() function examines the character given as its first
	* argument and returns true if and only if the character represents
	* an number. This helper function should be relatively short.
	*
	* Returns true if the given character represents an number, false
	* otherwise.
	*/
	bool isnumber(char c);
	/*
	* The decode() function takes a run-length encoded string as its
	* argument, parses every integer n preceding every character in
	* the string, and prints each character n times. For example, if
	* the string passed to decode() is "1a3b", decode() will print
	* "abbb". It returns an integer that represents the summed value
	* of the amount of characters printed; in this example, decode()
	* would return the integer 4.
	*
	* This function must also handle malformed run-length encoded strings.
	* A malformed string is any string which does not adhere to the RLE
	* implementation described in the handout. If a malformed string is
	* encountered, it should cease printing the decoded string, print an
	* error message, and return -1.
	*
	* Returns the integer value of the total amount of characters printed,
	* or -1 if the run-length encoded string is malformed.
	*/
	int decode(char *str);
	/*
	* The main function is where C programs begin.
	*
	* This function parses its arguments and returns the value they
	* represent. In this assignment, the only valid argument is a
	* run-length encoded string. Any extra arguments in excess of
	* this single valid argument make the invocation of your program
	* invalid.
	*
	* Remember that the argument in argv[0] is the name of the program, so
	* a program passed exactly one argument on the command line will
	* receive _two_ arguments: its name in argv[0] and the provided
	* argument in argv[1].
	*
	* Arguments:
	* argc - The number of arguments received
	* argv - The arguments received as an array of C strings
	*
	* Returns 0 if the argument is well-formed and the string could
	* be decoded, non-zero otherwise.
	*/
	int main(int argc, char *argv[]) {
	/* Your main program logic should go here, with helper logic in the
	* functions isnumber() and decode(), which you can place below
	* the closing brace of main() */
	return 0;
	}
	/* You should implement isnumber() and decode() here */

Note that there is a C library function that could perform the role of isnumber() called isdigit(), and several C library functions that can parse the integers in the RLE string into C integers, including atoi() and strtol(). but you can not use that on it . !!!!!!!!!

input could be like 431a34b4c or just 2a3b2c those are valid but 0a2b no!!!!

using c programming language to do this run length decoding ....