#include <stdio.h>

#define PutC(c)  (putc( (char) (c), stdout))
#define GetC()   (getc(stdin))
#define EMPTYLOOP {}
#define PutD(d)  (PutC('0'+(d)))

int PutV_u(unsigned int n)
{
	unsigned int m;
	int i, count;

	/* Set m to the largest power or ten <= n */
	for (m = 1; n/m >=10; m*=10)
		/* EMPTYLOOP */;

	/* Print out the digits in n one-by-one */
	for (count = 0; m > 0; m /= 10)
	{
		for(i = 0; n >= m; i++)
			n -= m;
		PutD(i);
		count++;
	}

	return count;
}

int PutV_i(int n)
{
	if (n < 0)
	{
		PutC('-');
		return 1 + PutV_u(-n);
	}

	return PutV_u(n);
}

int PutS(char *s)
{
	int i;

	for (i = 0; s[i] != '\0'; i++)
		PutC(s[i]);

	return i;
}

int main(void)
{
	int i;
	char *TheString;
	char StaticString[81];
	int *jp, *kp;
	int maxlen, c;

	PutS("Fun with strings\n\n");
	PutS("EXAMPLE #1 - Literal Strings\n");
	TheString = "A string literal";
	PutS("The String is: [");
	PutS(TheString);
	PutS("]\n\n");
	/* return; */

	PutS("EXAMPLE #2 - Statically Allocated Space\n");
	for (i = 'A'; i < 'Z'; i++)
		StaticString[i-'A'] = i;
	StaticString[i-'A'] = '\0';
	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n\n");
	/* return; */

	PutS("EXAMPLE #3 - Partway into the String\n");
	PutS("The String is: [");
	PutS(&StaticString['N'-'A']);
	PutS("]\n\n");
	/* return; */

	PutS("EXAMPLE #4 - Data Collision\n");

	/* Assigning the data pointed to by jp and kp to be within
		the space allocated to StaticString */

	jp = &StaticString[16];  /* Array notation   */
	kp = StaticString + 40;  /* Pointer notation */

	*jp = 4242;
	*kp = 42;

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("EXAMPLE #5 - Intentional Cross-representation\n");
	*jp = 'q' + 'r'*256;
	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("Attempt #1 - Getting a string from the keyboard\n");
	PutS("             Character by character until newline is read.\n");
	PutS("Enter String: ");
	i = 0;
	do
	{
		StaticString[i++] = GetC();
	} while (StaticString[i-1] != '\n');
	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("Attempt #2 - Getting a string from the keyboard\n");
	PutS("             Character by character until newline is read.\n");
	PutS("             Append the null terminator.\n");
	PutS("Enter String: ");
	i = 0;
	do
	{
		StaticString[i++] = GetC();
	} while (StaticString[i-1] != '\n');
	StaticString[i] = '\0';

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("Attempt #3 - Getting a string from the keyboard\n");
	PutS("             Character by character until newline is read.\n");
	PutS("             Append the null terminator.\n");
	PutS("             Exclude the trailing newline.\n");
	PutS("Enter String: ");
	i = 0;
	do
	{
		StaticString[i++] = GetC();
	} while (StaticString[i-1] != '\n');
	StaticString[i-1] = '\0';

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("Attempt #4 - Getting a string from the keyboard\n");
	PutS("             Character by character until newline is read.\n");
	PutS("             Append the null terminator.\n");
	PutS("             Exclude the trailing newline.\n");
	PutS("             Prevent Buffer Overrun.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < maxlen) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");

	PutS("Attempt #4A - Getting a string from the keyboard\n");
	PutS("              Character by character until newline is read.\n");
	PutS("              Append the null terminator.\n");
	PutS("              Exclude the trailing newline.\n");
	PutS("              Prevent Buffer Overrun.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < maxlen) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");

	/* return; */

	PutS("Attempt #5 - Getting a string from the keyboard\n");
	PutS("             Character by character until newline is read.\n");
	PutS("             Append the null terminator.\n");
	PutS("             Exclude the trailing newline.\n");
	PutS("             Prevent buffer overrun.\n");
	PutS("             Leave Room for the null-terminator.\n");
	PutS("             Clear input buffer of remaining characters.\n");
	PutS("Enter String: ");
	*kp = 28000;
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';
	while ( '\n' != c )
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");

	PutS("Attempt #5A - Getting a string from the keyboard\n");
	PutS("              Character by character until newline is read.\n");
	PutS("              Append the null terminator.\n");
	PutS("              Exclude the trailing newline.\n");
	PutS("              Prevent buffer overrun.\n");
	PutS("              Leave Room for the null-terminator.\n");
	PutS("              Clear input buffer of remaining characters.\n");
	PutS("Enter String: ");
	*kp = -32000;
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';
	while ( '\n' != c )
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("Attempt #6 - Getting a string from the keyboard\n");
	PutS("             Character by character until newline is read.\n");
	PutS("             Append the null terminator.\n");
	PutS("             (scratch) Exclude the trailing newline.\n");
	PutS("             Prevent buffer overrun.\n");
	PutS("             Leave Room for the null-terminator.\n");
	PutS("             Clear input buffer of remaining characters.\n");
	PutS("             Include newline character to mark success.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	if ( i < (maxlen-1) )
		StaticString[i++] = c;
	StaticString[i] = '\0';
	while ( '\n' != c )
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");

	PutS("Attempt #6A - Getting a string from the keyboard\n");
	PutS("              Character by character until newline is read.\n");
	PutS("              Append the null terminator.\n");
	PutS("              (scratch) Exclude the trailing newline.\n");
	PutS("              Prevent buffer overrun.\n");
	PutS("              Leave Room for the null-terminator.\n");
	PutS("              Clear input buffer of remaining characters.\n");
	PutS("              Include newline character to mark success.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	if ( i < (maxlen-1) )
		StaticString[i++] = c;
	StaticString[i] = '\0';
	while ( '\n' != c )
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("Attempt #7 - Getting a string from the keyboard\n");
	PutS("             Character by character until newline is read.\n");
	PutS("             Append the null terminator.\n");
	PutS("             Prevent buffer overrun.\n");
	PutS("             Leave Room for the null-terminator.\n");
	PutS("             Clear input buffer of remaining characters.\n");
	PutS("             Exclude newline character.\n");
	PutS("             Count the number of characters discarded.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';
	for ( *jp = 0; '\n' != c; (*jp)++ ) /* Pointer Notation */
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");

	PutS("Attempt #7A - Getting a string from the keyboard\n");
	PutS("              Character by character until newline is read.\n");
	PutS("              Append the null terminator.\n");
	PutS("              Prevent buffer overrun.\n");
	PutS("              Leave Room for the null-terminator.\n");
	PutS("              Clear input buffer of remaining characters.\n");
	PutS("              Exclude newline character.\n");
	PutS("              Count the number of characters discarded.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';
	for ( jp[0] = 0; '\n' != c; jp[0]++ ) /* Array Notation */
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	PutS("Attempt #7B - Getting a string from the keyboard\n");
	PutS("              Character by character until newline is read.\n");
	PutS("              Append the null terminator.\n");
	PutS("              Prevent buffer overrun.\n");
	PutS("              Leave Room for the null-terminator.\n");
	PutS("              Clear input buffer of remaining characters.\n");
	PutS("              Exclude newline character.\n");
	PutS("              Count the number of characters discarded.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';
	for ( *kp = 0; '\n' != c; (*kp)++ ) /* Pointer Notation */
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");

	PutS("Attempt #7C - Getting a string from the keyboard\n");
	PutS("              Character by character until newline is read.\n");
	PutS("              Append the null terminator.\n");
	PutS("              Prevent buffer overrun.\n");
	PutS("              Leave Room for the null-terminator.\n");
	PutS("              Clear input buffer of remaining characters.\n");
	PutS("              Exclude newline character.\n");
	PutS("              Count the number of characters discarded.\n");
	PutS("Enter String: ");
	maxlen = 40;
	i = 0;
	while ( (i < (maxlen-1)) && ('\n' != (c = GetC())) )
	{
		StaticString[i++] = c;
	}
	StaticString[i] = '\0';
	for ( kp[0] = 0; '\n' != c; kp[0]++ ) /* Array Notation */
		c = GetC();

	PutS("The String is: [");
	PutS(StaticString);
	PutS("]\n");
	PutS("The value pointed to by jp: <");
	PutV_i(*jp);
	PutS(">\n");
	PutS("The value pointed to by kp: <");
	PutV_i(*kp);
	PutS(">\n\n");
	/* return; */

	return 0;
}