// CS 350, Spring 2012
// Lab 1 -- Introduction to C

#include <stdio.h>		// to access printf, scanf
#include <string.h>		// to access strlen, strcmp
	/* Note: strcmp(s1, s2) compares two strings s1 and s2 and returns 0
	   if the strings are equal; it returns a value < 0 if s1 is less than s2;
	   it returns a value > 0 if s1 is greater than s2. [Here, "less than"
	   and "greater than" refer to lexicographic ordering -- we compare the
	   strings character by character from left to right.] */

void handle(char str[], int m);	// (function prototype)

int main(void) {
	// Read in a floating-point and double precision floating-point number
	// (using the %f and %lf (long float) formats respectively).
	// Echo the values, find the larger of the two, and print it out in
	// exponential format.
	//
	float x;
	double y;
	printf("Enter two floating point numbers (separated by white space and followed by a carriage return): ");
	scanf("%f %lf", &x, &y);
	printf("You entered %f and %lf; the larger of the two is %le\n", x, y, (x > y ? x : y));

	// We repeatedly read and handle an integer and string typed in by the user.
	// We quit if the user enters q as the string.
	//
	int m;
	char str[256] = "";				// Space for a string of length <= 255
	printf("Enter an integer, some white space, a string (q to quit) and a carriage return: ");
	scanf("%d %s", &m, str);		// read m and the input string

	while (strcmp(str, "q")) {		// while string is not "q"
		handle(str, m);				// call subroutine to handle string and m
		printf("Enter an integer and a string (q to quit): ");
		scanf("%d %s", &m, str);	// read next str and m
	}
	return 0;
}

// handle(str, m) takes a string and an index m.  It prints out the length
// of the string, prints out the character at position m of the string (if
// m is in bounds), figures out which character of the string is the largest
// (using the ASCII encoding), and prints out the largest character both in
// character and integer form.
//
void handle(char str[], int m) {
		// Calculate and print out the string's length.
		//
		int len = strlen(str);
		printf("%s has length %d.  ", str, len);

		// If the index m is legal for str, print str[m], else
		// say that m is out of bounds.
		//
		if (m < 0 || m >= len) {
			printf("Index %d is outside the string.\n", m);
		}
		else {
			printf("Character %d of the string is %c\n", m, str[m]);
		}

		// If str isn't the empty string, find its largest character
		// and print it out in character and integer form.
		//
		if (strcmp(str, "") == 0) {			// or, if len == 0
			printf("The string is empty\n");
		}
		else {
			int i;							// 0 <= i < len
			char max = str[0];				// max = largest char of str[0..i]
			for (i = 1 ; i < len ; i++) {
				if (max < str[i])
					max = str[i];			// reestablish max for current i
			}
			printf("The largest character of %s is %c; it has numeric value %d\n",
				str, max, (int) max );
		}
}