Makefile_练习 _0228

//Makefile

#练习编写Makefile文件

src = $(wildcard *.c)
targets = $(patsubst %.c, %, $(src))

CC = gcc
CFLAGS = -Wall -g

all:$(targets)
$(targets):%:%.c
    $(CC) $(CFLAGS) $< -o $@
clean:
    rm $(targets)
.PHONY:clean

//endian.c
//测机器的大小端

#include <stdio.h>

int main(int argc, const char *argv[])
{
    int n = 0x1234567, *p;
    p = &n;

    if(*(short*)p == 0x1234)
        printf("big endian\n");
    else
        printf("little endian\n");
    return 0;
}

//partition.c
//用位操作，将一个32位数，分割成两个数

#include <stdio.h>

void partition(unsigned int n)
{
    unsigned int a, b;
    a = n & 0xffff;
    b = (n >> 16) & 0xffff;
    printf("%#x\n", a);
    printf("%#x\n", b);
}


int main(int argc, const char *argv[])
{
    unsigned int n;

    printf("n=0x");
    scanf("%x", &n);

    partition(n);
    return 0;
}

//show.c
//将一个数，逆序输出

#include <stdio.h>

int main(int argc, const char *argv[])
{
    int  n, num = 0, tmp, i;
    int  arr[5] = {0};

    printf("n=");
    scanf("%d", &n);

    tmp = n;

    do{
        num++;
        if(num > 5)
            break;
        arr[num-1] = tmp%10;
        tmp/=10;
      }while(tmp);

    if(num > 5)
        printf("the numbers of n: (1~5)\n");
    else
    {
        printf("forward: %d\n",n);
        printf("reverse: ");
        i = 0;
        while(arr[i])
        {
            printf("%d",arr[i]);
            i++;
        }
        printf("\n");
    }


    return 0;
}