Handout 12c

more qsort

#include <iostream.h>
#include <string.h>
#include <stdlib.h>

// function prototypes
int compareStringVariables( const void *, const void *);
int compareFloatingPointVariables( const void *, const void *);

void main(void) {

	const int buf_size = 100; // maximum input line length
	char name[buf_size]; // input buffer for user sentence

	char wordArray[50][25]; // 50 words, each 24 long

	char * p; // character pointer for strtok
	char tok_vals[] = " \t\n.?,"; // separators for strtok

	int wordsFound = 0; // number of user words found
	int i; // index variable

	// Notice that the output buffer is flushed.
	cout << "\n Enter some words (each word max 24 characters):" << endl;
	cin.getline(name, buf_size); // get the input line

	// tokenize the input sentence

	// strtok places a NULL terminator in front of the token, if found  
	p = strtok(name, tok_vals);

	while(p != NULL) {

		// put words into word array
		strcpy(wordArray[wordsFound],p);

		wordsFound++;
	   
		// Subsequent calls to strtok using a NULL as the first parameter
		// returns a pointer to the character following the token   
		p = strtok(NULL, tok_vals);
	}

	// verify word count
	cout << endl << "You have input " << wordsFound << " words" << endl;


	// sort the list of words
	qsort((void *)wordArray, 
		wordsFound, 
		sizeof(wordArray[0]), 
		compareStringVariables);
	
	
	// print out list of sorted words
	cout << "List of sorted wqords" << endl;
	for(i = 0; i < wordsFound; i++) {
		cout << wordArray[i] << endl;
	}


	// get some floating point values from the user
	float theValues[100];
	int valueCount = 0;

	cout << endl << "Give me some floating point values, 0.0 to end" << endl;

	cin >> theValues[valueCount];

	while(theValues[valueCount] != 0) {

		valueCount++;
		cin >> theValues[valueCount];
	}

	// verify value count
	cout << endl << "You have input " << valueCount << " values" << endl;

	// sort the list of values
	qsort((void *)theValues, 
		valueCount, 
		sizeof(theValues[0]), 
		compareFloatingPointVariables);

	// print out list of sorted values
	cout << "List of sorted words" << endl;
	for(i = 0; i < valueCount; i++) {
		cout << theValues[i] << endl;
	}
}

int compareStringVariables( const void *a, const void *b) {

	// This comparison function must return a negative value if a is less than b, 
	// zero if the two are equal, or a positive value if a is greater than b. Two array
	// elements that are equal can appear in the sorted array in either order.
   
	return( strcmp((char *)a,(char *)b) );
}

int compareFloatingPointVariables( const void *a, const void *b) {

	// This comparison function must return a negative value if a is less than b, 
	// zero if the two are equal, or a positive value if a is greater than b. Two array
	// elements that are equal can appear in the sorted array in either order.
   
	if( *((float *) a) < *((float *) b)) return -1;
	if( *((float *) a) > *((float *) b)) return 1;
	else return 0;
}

* source code is here.