I am trying to compile the following multi-file program (taken from the book Programming: a Modern approach, second edition By K. N. King) with a Makefile, but the compilation fails and I get the following warnings and don't understand why:
clang: warning: readline.o: 'linker' input unused [-Wunused-command-line-argument]clang: warning: inventory2.o: 'linker' input unused [-Wunused-command-line-argument]clang: warning: argument unused during compilation: '-Wall' [-Wunused-command-line-argument]here is the makefile:
############# makefile #############CC = gccCFLAGS = -c -WallBIN=inventory2$(BIN): $(BIN).o readline.o #readline.h $(CC) $(CFLAGS) readline.o $(BIN).o -o $(BIN)$(BIN).o: $(BIN).c $(CC) $(CFLAGS) $(BIN).c -o $(BIN).oreadline.o: readline.c readline.h $(CC) $(CFLAGS) readline.c -o readline.oclean: $(RM) -rf $(BIN) *.dSYM $(RM) -rf readline.o $(RM) -rf $(BIN).orun: all ./$(BIN)Here are the source files (inventory2.c, readline.c and readline.h)
/********************************************************* * From C PROGRAMMING: A MODERN APPROACH, Second Edition * * By K. N. King * * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. * * All rights reserved. * * This program may be freely distributed for class use, * * provided that this copyright notice is retained. * *********************************************************//* inventory.c (Chapter 16, page 391) *//* Maintains a parts database (array version) */#include <stdio.h>#include "readline.h"#define NAME_LEN 25#define MAX_PARTS 100struct part { int number; char name[NAME_LEN+1]; int on_hand;} inventory[MAX_PARTS];int num_parts = 0; /* number of parts currently stored */int find_part(int number);void insert(void);void search(void);void update(void);void print(void);/********************************************************** * main: Prompts the user to enter an operation code, * * then calls a function to perform the requested * * action. Repeats until the user enters the * * command 'q'. Prints an error message if the user * * enters an illegal code. * **********************************************************/int main(void){ char code; for (;;) { printf("Enter operation code: "); scanf(" %c", &code); while (getchar() != '\n') /* skips 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"); } printf("\n"); }}/********************************************************** * find_part: Looks up a part number in the inventory * * array. Returns the array index if the part * * number is found; otherwise, returns -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: Prompts the user for information about a new * * part and then 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(void){ 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: Prompts the user to enter a part number, then * * looks up the part in the database. If the part * * exists, prints the name and quantity on hand; * * if not, prints an error message. * **********************************************************/void search(void){ int i, number; printf("Enter part number: "); scanf("%d", &number); i = find_part(number); if (i >= 0) { printf("Part name: %s\n", inventory[i].name); printf("Quantity on hand: %d\n", inventory[i].on_hand); } else printf("Part not found.\n");}/********************************************************** * update: Prompts the user to enter a part number. * * Prints 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(void){ int i, number, change; printf("Enter part number: "); scanf("%d", &number); i = find_part(number); if (i >= 0) { printf("Enter change in quantity on hand: "); scanf("%d", &change); inventory[i].on_hand += change; } else printf("Part not found.\n");}/********************************************************** * print: Prints 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(void){ int i; printf("Part Number Part Name ""Quantity on Hand\n"); for (i = 0; i < num_parts; i++) printf("%7d %-25s%11d\n", inventory[i].number, inventory[i].name, inventory[i].on_hand);}File readline.c:
/********************************************************* * From C PROGRAMMING: A MODERN APPROACH, Second Edition * * By K. N. King * * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. * * All rights reserved. * * This program may be freely distributed for class use, * * provided that this copyright notice is retained. * *********************************************************//* readline.c (Chapter 16, page 395) */#include <ctype.h>#include <stdio.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;}and readline.h:
/********************************************************* * From C PROGRAMMING: A MODERN APPROACH, Second Edition * * By K. N. King * * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. * * All rights reserved. * * This program may be freely distributed for class use, * * provided that this copyright notice is retained. * *********************************************************//* readline.h (Chapter 16, page 395) */#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. Returns the number of * * characters stored. * **********************************************************/int read_line(char str[], int n);#endif