binary to decimal

I need some help I need to write a program that a user inputs a string of 32 0's and 1's representing a binary number. then I need to convert the binary integer to its base 10 representation and then back.

#include <stdio.h> #include <stdlib.h> #include <string.h> long BinaryToDecimal(const char * pstrBinary) { int intLoop=0; long lngReturn=0L; long lngMultip=1L; for (intLoop=0; intLoop < (int)strlen(pstrBinary); intLoop++) { if ('1' == pstrBinary[intLoop]) { lngReturn += lngMultip; } lngMultip *= 2; } return lngReturn; } char * DecimalToBinary(long lngDecimal) { static char strReturn[128]={0}; _ltoa(lngDecimal, strReturn, 2); return strReturn; } int main(void) { long lngDecimal = 7; char * pstrBinary = "111"; printf("B2D=%ld\nD2B=%s\n", BinaryToDecimal(pstrBinary),DecimalToBinary(lngDecimal)); }

What exactly is the problem?