from binary string to decimal integer.

bin2dec.c

#include <stdio.h>
#include <stdlib.h>

unsigned long bin2dec(const char *binary)
{
	unsigned long decimal = 0;
	do {
		if ( *binary == '0' ) {
			decimal <<= 1;
		} else if ( *binary == '1' ) {
			decimal <<= 1;
			decimal += 1;
	        } else if ( *binary == ' ' ) {
        	    ;
		} else {
			break;
		}
	} while ( *(++binary) != 0 );
	return decimal;
}

int main(int argc,char *argv[])
{
	if ( argc < 2 ) {
		fprintf(stderr,"Usage:%s binnumber\n",argv[0]);
		return 1;
	}
//	unsigned long dec = strtoul(argv[1],NULL,2);
	unsigned long dec = bin2dec(argv[1]);
	printf("%ld\n",dec);
	return 0;
}