GNU Make

作者:

試做一個小範例

首先要先安裝 makefile 的套件

sudo apt install make

分別建立以下四個檔案

#include "myprogram.h"
int compute(int grade){
return 0.5 * grade;
}
#include "stdio.h"
#include "myprogram.h"
int foo(int grade){
printf("Grade is %d\n", compute(grade));
return 0;
}
#include "stdio.h"
#include "myprogram.h"
int main(void){
int grade=60;
foo(grade);
return 0;
}
int foo(int);
int compute(int);

然後再新增一個 makefile 的檔案(第一版)，輸入以下的程式碼

all:myprogram
myprogram: main.o foo.o compute.o
gcc -o myprogram main.o foo.o compute.o
main.o: main.c myprogram.h
gcc -c main.c
foo.o: foo.c myprogram.h
gcc -c foo.c
compute.o: compute.c myprogram.h
gcc -c compute.c

使用手動的方式編譯程式(建立 linker)

gcc -c main.c
gcc -c foo.c
gcc -c compute.c
gcc-o myprogram main.o foo.o compute.o
./myprogram

使用 makefile 自動編譯程式

首先要刪除掉舊的 .o 檔案

rm main.o foo.o compute.o

然後輸入以下指令

make all

再來要做第二版的 makefile，修改剛剛的 makefile 檔案為以下

CC=gcc
CFLAGS=-O
COMPILE=$(CC) $(CFLAGS) -c
all:myprogram
myprogram: main.o foo.o compute.o
$(CC) -o myprogram main.o foo.o compute.o
main.o: main.c myprogram.h
$(COMPILE) main.c
foo.o: foo.c myprogram.h
$(COMPILE) foo.c
compute.o: compute.c myprogram.h
$(COMPILE) -c compute.c
clean:
rm -f *.o

儲存之後輸入以下程式碼清除 .o 檔案

make clean

然後再輸入以下程式碼編譯檔案

make all
./myprogram

GDB 除錯

首先建立一個檔案 eq.c

#include <stdio.h>
int main()
{
int a, b, c;
a=5;
b=10;
b+=a;
c=b+a;
return 0;
}

輸入以下指令編譯可供除錯的執行檔案

gcc -g eq.c -o eq

再來輸入以下指令進入除錯模式

gdb eq

再來輸入以下指令查看程式碼

l
或是
list

以下是 GDB 的中斷點用法

GDB 練習

stust@ubuntu:~/test$ gdb myprogram 
GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2.1) 7.4-2012.04
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type “show copying”
and “show warranty” for details.
This GDB was configured as “i686-linux-gnu”.
For bug reporting instructions, please see:
<http://bugs.launchpad.net/gdb-linaro/>…
Reading symbols from /home/stust/test/myprogram…done.
(gdb) l
1    #include <stdio.h>
2    #include “myprogram.h”
3    
4    
5    int main(void) {
6        int grade=60;
7        foo(grade);
8        return 0;
9    }
(gdb) b foo
Breakpoint 1 at 0x804840e: file foo.c, line 5.
(gdb) run
Starting program: /home/stust/test/myprogram Breakpoint 1, foo (grade=60) at foo.c:5
5        printf(“Grade is %d\n”, compute(grade));
(gdb) l
1    #include <stdio.h>
2    #include “myprogram.h”
3    
4    int foo(int grade) {
5        printf(“Grade is %d\n”, compute(grade));
6        return 0;
7    }
(gdb) b compute
Breakpoint 2 at 0x804843a: file compute.c, line 4.
(gdb) c
Continuing.Breakpoint 2, compute (grade=60) at compute.c:4
4        grade = grade +10;
(gdb) list
1    #include “myprogram.h”
2    
3    int compute(int grade) {
4        grade = grade +10;
5        return 1.5 * grade;
6    }
(gdb) p grade
$1 = 60
(gdb) disp grade
1: grade = 60
(gdb) n
5        return 1.5 * grade;
1: grade = 70
(gdb) n
6    }
1: grade = 70
(gdb) c
Continuing.
Grade is 105
[Inferior 1 (process 3461) exited normally]
(gdb) 

SHXJ
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