A Simple Program To Print Integer In Binary

binary.c

#include <stdio.h>

void printBinary(int);
int toInt(int*, char[]);
int handleProgram(char[]);

int main(int argc, char *argv[])
{	
	return handleProgram(argv[1]);
}

int handleProgram(char param[])
{
	int number, state;
	
	if( toInt( &number, param ) != -1 )
	{
		printBinary(number);
		
		state = 0;
	}
	else
	{
		printf("\tmain()::Exiting program...\n");
		
		state = -1;
	}
	
	return state;
}


void printBinary(int number)
{
	for (int i = 31; i >= 0; i--)
	{
		if (number >> i & 1 == 1)
			putchar('1');
		else
			putchar('0');

		if (i != 0)
		{
			if (i % 4 == 0)
				putchar(' ');

			if (i % 16 == 0)
				printf(": ");
		}
	}

	printf("\n");
}

int toInt(int *num, char param[])
{
	*num = 0;
	int sign = 1;
	int i = 0;
	
	if(param == NULL)
	{
		printf("\ttoInt()::No parameter, please enter a valid number!\n");
		
		return -1;
	}
	
	if(param[i] == '-')
	{
		sign = -1;
		i++;
	}
	else if( param[i] == '+' )
	{
		i++;
	}
	
	// check that a number exist
	if(param[i] == '\0')
	{
		printf("\ttoInt()::No number detected, please enter a valid number\n");
		
		return -1;
	}
	
	for(; param[i] != '\0'; i++)
	{
		if(param[i] >= '0' && param[i] <= '9')
			*num = 10* *num + param[i] - '0';
		else
		{
			printf("\ttoInt()::Invalid parameter, please enter a valid number!\n");
			
			return -1;
		}
	}
	
	*num *= sign;
	
	return 0;
}

Sample Output;

D:\C\chapter2>gcc binary.c -o binary.exe

D:\C\chapter2>binary 3
0000 0000 0000 0000 : 0000 0000 0000 0011

D:\C\chapter2>binary +3
0000 0000 0000 0000 : 0000 0000 0000 0011

D:\C\chapter2>binary -3
1111 1111 1111 1111 : 1111 1111 1111 1101

D:\C\chapter2>binary +3s
toInt()::Invalid parameter, please enter a valid number!
main()::Exiting program...

D:\C\chapter2>binary -3s
toInt()::Invalid parameter, please enter a valid number!
main()::Exiting program...

D:\C\chapter2>binary s
toInt()::Invalid parameter, please enter a valid number!
main()::Exiting program...

D:\C\chapter2>binary +
toInt()::No number detected, please enter a valid number
main()::Exiting program...

D:\C\chapter2>binary -
toInt()::No number detected, please enter a valid number
main()::Exiting program...

D:\C\chapter2>binary
toInt()::No parameter, please enter a valid number!
main()::Exiting program...