homework's first working version

homework2/main2.c

+#include <stdio.h> 
+#include <stdlib.h>
+
+char ** generate_brands(int);
+float * set_prices(int, char **, float *);
+float read_discount();
+void display_data(char **, float *, float *, int, int);
+float * calculate_prices(float *, float *, float, int);
+
+int main(void) {
+	int arraySize = 8;
+	char ** brands = generate_brands(arraySize);
+	float * prices = malloc(arraySize*sizeof(float *));
+	prices = set_prices(arraySize, brands, prices);
+	float discount = read_discount();
+	float * new_prices = malloc(arraySize*sizeof(float *));
+	display_data(brands, prices, new_prices, arraySize, 0);
+	new_prices = calculate_prices(prices, new_prices, discount, arraySize);
+	display_data(brands, prices, new_prices, arraySize, 1);
+}
+
+char **generate_brands(int arraySize) {
+	char ** brands =  (char **)malloc(arraySize*sizeof(char *));
+	brands[0] = "Samsung";
+	brands[1] = "LG";
+	brands[2] = "Panasonic";
+	brands[3] = "Toshiba";
+	brands[4] = "Philips";
+	brands[5] = "Sharp";
+	brands[6] = "Visio";
+	brands[7] = "Mitsubishi";
+	return brands; 
+}
+
+float *set_prices(int arraySize, char **brands, float * prices) {
+
+	for(int i = 0; i < arraySize; i++) {
+		printf("Enter the price for %s\n", *brands);
+			scanf("%f", prices);
+		while((int)*prices <= 0) {
+			printf("No, the price can be neither zero nor negative. Be realistic: ");
+			scanf("%f", prices);
+		}
+		brands++;
+		prices++;
+	}
+	return (float *)((int)prices - arraySize*sizeof(float *));
+}
+
+float read_discount() {
+	float input;
+	printf("Enter the discount: ");
+	scanf("%f", &input);
+	if(input < 10 || input > 60) {
+		printf("Invalid discount.\n");
+		return read_discount();
+	}
+	return input;
+}
+
+void display_data(char ** brands, float * prices, float * new_prices, int arraySize, int if_new) {
+	if(if_new == 0) {
+		printf("\n    TV Brand\tOld price\n");
+		for(int i = 0; i < arraySize; i++) {
+			printf("%12s \t%.1f \n", *brands, *prices);
+			brands++;
+			prices++;
+		}
+	} else {
+		printf("\n    TV Brand\tNew price\n");
+		for(int i = 0; i < arraySize; i++) {
+			printf("%12s \t%.1f \n", *brands, *new_prices);
+			brands++;
+			new_prices++;
+		}
+	}
+}
+
+float *calculate_prices(float * prices, float * new_prices, float discount, int arraySize) {
+	for(int i = 0; i < arraySize; i++) {
+		*new_prices = *prices * (1 - (discount/100.0));
+		prices++;
+		new_prices++;
+	}
+	return (float *)((int)new_prices - arraySize*sizeof(float *));
+}
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