4-17

code/practise/16 结构&联合&枚举/01 维护零件数据库/inventory.c

@@ -0,0 +1,194 @@
+#define _CRT_SECURE_NO_WARNINGS 1
+
+#include<stdio.h>
+#include"readline.h"
+
+#define NAME_LEN 20
+#define MAX_PARTS 100
+
+struct part {
+	int number;
+	char name[NAME_LEN + 1];
+	int on_hand;
+}inventory[MAX_PARTS];
+
+int num_parts = 0; //number of parts current stored
+
+void menu();
+int find_part(int number);
+void insert();
+void search();
+void update();
+void print();
+
+
+int main(void) {
+	
+	char code = 'a';
+
+	menu();
+
+	for (;;) {
+		printf("Enter operation code: ");
+		scanf(" %c", &code);
+		while (getchar() != '\n') // ships to end of line
+			;
+		switch (code) {
+			case 'i': insert(); break;
+			case 's': search(); break;
+			case 'u': update(); break;
+			case 'p': print(); break;
+			case 'q': return 0;
+			default: printf("Illegal code.\n"); break;
+		}
+	}
+
+
+
+
+	return 0;
+}
+
+void menu() {
+
+	printf("                        ==================================\n");
+	printf("                        *                                *\n");
+	printf("                        *            i:  insert          *\n");
+	printf("                        *            s:  search          *\n");
+	printf("                        *            u:  undate          *\n");
+	printf("                        *            p:  print           *\n");
+	printf("                        *            q:  quit            *\n");
+	printf("                        *                                *\n");
+	printf("                        ==================================\n");
+}
+
+
+/**********************************************************
+*
+*	find_part: Looks up a part number in the inventory
+*			   array.Returns the array index if the part
+*			   number is found;otherwise,return -1
+*
+***********************************************************/
+int find_part(int number) {
+
+	int i;
+
+	for (i = 0; i < num_parts; i++) {
+		if (inventory[i].number == number)
+			return i;
+	}
+
+	return -1;
+}
+
+
+/**********************************************************
+*
+*	insert: Inserts the part into the database.Prints
+*		    an error message and returns prematurely
+*			if the part already exists or the database
+*			is full.
+*
+***********************************************************/
+void insert() {
+	
+	int part_number;
+
+	if (num_parts == MAX_PARTS) {
+		printf("Database is full; can't add more parts.\n");
+		return;
+	}
+
+	printf("Enter part number: ");
+	scanf("%d", &part_number);
+
+	if (find_part(part_number) >= 0) {
+		printf("Part already exists.\n");
+		return;
+	}
+
+	inventory[num_parts].number = part_number;
+	printf("Enter part name: ");
+	read_line(inventory[num_parts].name, NAME_LEN);
+	printf("Enter quantity on hand: ");
+	scanf("%d", &inventory[num_parts].on_hand);
+	num_parts++;
+}
+
+
+/************************************************************
+*
+*	search: Look up a part by the number user enters.
+*			If the part exists, prints the name and quantity
+*			on hand;if not, print an error message.
+*
+************************************************************/
+void search() {
+	
+	int index, number;
+
+	printf("Enter part number: ");
+	scanf("%d", &number);
+
+	index = find_part(number);
+
+	if (index == -1) {
+		printf("Part not found.\n");
+		return;
+	}
+	
+	printf("Part name: %s\n", inventory[index].name);
+	printf("Quantity on hand: %d\n", inventory[index].on_hand);
+	
+}
+
+
+/************************************************************
+*
+*	update: Prompts user to enter a number.
+*			Print an error message if the part doesn't exist;
+*			otherwise,prompts the user to enter change in
+*			quantity on hand and updates the database.
+*
+************************************************************/
+
+void update() {
+	
+	int number, index, change;
+
+	printf("Enter part number: ");
+	scanf("%d", &number);
+
+	index = find_part(number);
+
+	if (index == -1) {
+		printf("Part not found.\n");
+		return;
+	}
+
+	printf("Enter change in quantity on hand(- means minus): ");
+	scanf("%d", &change);
+	inventory[index].on_hand += change;
+
+}
+
+
+/************************************************************
+*
+*	print: Print a listing of all parts in the database,
+*		   showing the part number,part name and quantity
+*		   on hand.Parts are printed in the order in which
+*		   they were entered into the database.
+*
+************************************************************/
+
+void print() {
+	
+	int i;
+
+	printf("Part Number      Part Name      Quantity on Hand\n");
+	for (i = 0; i < num_parts; i++) {
+		printf("%6d%20s%15d\n", inventory[i].number, inventory[i].name, inventory[i].on_hand);
+	}
+}

code/practise/16 结构&联合&枚举/01 维护零件数据库/readline.c

@@ -0,0 +1,24 @@
+#define _CRT_SECURE_NO_WARNINGS 1
+
+#include<stdio.h>
+#include<ctype.h>
+#include"readline.h"
+
+int read_line(char str[], int n) {
+
+	int ch, i = 0;
+
+	while (isspace(ch = getchar()))
+		;
+
+	while (ch != '\n' && ch != EOF) {
+		if (i < n) 
+			str[i++] = ch;
+
+		ch = getchar();
+	}
+	str[i] = '\0';
+
+	return i;
+}
+

code/practise/16 结构&联合&枚举/01 维护零件数据库/readline.h

@@ -0,0 +1,16 @@
+#ifndef READLINE_H
+#define READLINE_H
+
+/***********************************************************
+*
+*	read_line: Skips leading white-space characters, then
+*			   reads the remainder of the input line and
+*			   stores it in str. Truncates the line if its
+*			   length exceeds n. Return the number of 
+*			   characters stores.
+*
+***********************************************************/
+
+int read_line(char str[], int n);
+
+#endif

code/practise/16 结构&联合&枚举/01 维护零件数据库/readme.md

@@ -0,0 +1,51 @@
+#### 程序：维护零件数据库
+
+此程序用来维护仓库存储的零件信息的数据库。程序围绕一个结构数组构建，且每个结构包含以下信息：零件编号，名称和数量。程序将支持下列操作：
+
+- **添加新零件信息**。如果零件已经存在，或数据库已满，显示出错信息。
+- **给定零件编号，显示零件的名称，数量信息**。如果零件编号不存在，那么给出出错信息。
+- **给定零件编号，改变零件的数量**。如果零件编号不存在，给出出错消息。
+- **显示列出数据库中的全部信息**。零件必须按照录入顺序显示。
+- **终止程序的执行**
+
+使用：
+
+- `i`:插入
+- `s`:搜索
+- `u`:更新
+- `p`:显示
+- `q`:退出
+
+分表表示这种操作，与程序得到会话如下：
+
+```c
+Enter operation code: i
+Enter part number: 833
+Enter part name: Disk Drive
+Enter quantity on hand: 90
+Enter operation code: i
+Enter part number: 788
+Enter part name: USB 3.0
+Enter quantity on hand: 67
+Enter operation code: s
+Enter part number: 832
+Part not found.
+Enter operation code: 833
+Illegal code.
+Enter operation code: s
+Enter part number: 833
+Part name: Disk Drive
+Quantity on hand: 90
+Enter operation code: u
+Enter part number: 788
+Enter change in quantity on hand(- means minus): 3
+Enter operation code: p
+Part Number      Part Name      Quantity on Hand
+   833          Disk Drive             90
+   788             USB 3.0             70
+Enter operation code: q
+```
+
+注意：菜单可以没有
+
+因为 readline 函数和这个程序的主干没有太大关系，我们用单独的头文件和源文件包含它。