和菜鸟一起深入学习国嵌实验之文件编程

1、  文件创建

代码：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
 
void create_file(char *filename)
{
    //create a file
    if(creat(filename, 0666)< 0)
    {
        printf("createfile %s failure\n", filename);
        return;
    }
    else
    {
        printf("createfile %s success!\n", filename);
    }
}
 
 
int main(int argc, char *argv[])
{
    if(argc < 2)
    {
        printf("youhave't input the filename, please try again\n");
        exit(1);
    }
 
    create_file(argv[1]);
 
    return 0;
}

Makefile：

CC = gcc
 
CURTDIR = $(shell pwd)
TARGET = file_create
 
%.o:%.c
$(CC) -c $(EXTRAFLAGS) $<-o $@
%.o:%.S
$(CC) -c $(EXTRAFLAGS) $<-o $@
 
.PHONY: all clean
 
$(TARGET): $(TARGET).o
$(CC)  -o $@ $^
 
clean:
rm -rf $(TARGET) $(TARGET).o

运行结果：

eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.5$ make
gcc -c  file_create.c -ofile_create.o
gcc  -o file_createfile_create.o
 
eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.5$ ls
file_create file_create.c  file_create.o  Makefile
 
eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.5$./file_create file_cre
create file file_cre success!
 
eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.5$ ll
鎬荤敤閲?40
drwxr-xr-x 2 eastmoon eastmoon 4096 2013-01-29 19:39 ./
drwxr-xr-x 8 eastmoon eastmoon 4096 2013-01-29 19:29 ../
-rw-r--r-- 1 eastmoon eastmoon    0 2013-01-29 19:39 file_cre
-rwxr-xr-x 1 eastmoon eastmoon 7232 2013-01-29 19:38 file_create*
-rw-r--r-- 1 eastmoon eastmoon  571 2013-01-29 19:38 file_create.c
-rw-r--r-- 1 eastmoon eastmoon 1204 2013-01-29 19:38 file_create.o
-rw------- 1 eastmoon eastmoon 12288 2013-01-29 19:39 .file.txt.swp
-rw-r--r-- 1 eastmoon eastmoon  237 2013-01-29 19:31 Makefile

２、文件拷贝

代码：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
 
#define BUFFER_SIZE 1024
 
int main(int argc, char *argv[])
{
    FILE *from_fd;
    FILE *to_fd;
    long file_len = 0;
    char buffer[BUFFER_SIZE];
    char *ptr;
 
    if(argc != 3)
    {
        printf("Usage: %s form file tofile\n", argv[0]);
        exit(1);
    }
   
    //open source file
    if((from_fd =fopen(argv[1], "rb")) == NULL)
    {
        printf("Open %sError\n", argv[1]);
        exit(1);
    }
 
    //create dest file
    if((to_fd = fopen(argv[2],"wb")) == NULL)
    {
        printf("Open %sError\n", argv[1]);
        exit(1);
    }
 
    //test the file size
    fseek(from_fd, 0L,SEEK_END);
    file_len = ftell(from_fd);
    fseek(from_fd, 0L,SEEK_SET);
   
    printf("from filesize is %ld\n", file_len);
 
    //copy the file
    while(!feof(from_fd))
    {
        fread(buffer,BUFFER_SIZE, 1, from_fd);
        if(BUFFER_SIZE >=file_len)
        {
            fwrite(buffer,file_len, 1, to_fd);
        }
        else
        {
            fwrite(buffer,BUFFER_SIZE, 1, to_fd);
            file_len =file_len - BUFFER_SIZE;
        }
        bzero(buffer,BUFFER_SIZE);
    }
    fclose(from_fd);
    fclose(to_fd);
 
    return 0;
}

Makefile

CC = gcc
 
CURTDIR = $(shell pwd)
TARGET = file_cp
 
%.o:%.c
$(CC) -c $(EXTRAFLAGS) $<-o $@
%.o:%.S
$(CC) -c $(EXTRAFLAGS) $<-o $@
 
.PHONY: all clean
 
$(TARGET): $(TARGET).o
$(CC)  -o $@ $^
 
clean:
rm -rf $(TARGET) $(TARGET).o

运行结果：

eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.5$ make
gcc -c  file_cp.c -o file_cp.o
gcc  -o file_cp file_cp.o
 
eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.5$./file_cp  file_cp.c file_test.c
from file size is 1241
 
eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.5$ ll
鎬荤敤閲?44
drwxr-xr-x 2 eastmoon eastmoon 4096 2013-01-29 19:28 ./
drwxr-xr-x 7 eastmoon eastmoon 4096 2013-01-29 19:11 ../
-rwxr-xr-x 1 eastmoon eastmoon 7472 2013-01-29 19:27 file_cp*
-rw-r--r-- 1 eastmoon eastmoon 1241 2013-01-29 19:26 file_cp.c
-rw-r--r-- 1 eastmoon eastmoon 1868 2013-01-29 19:27 file_cp.o
-rw-r--r-- 1 eastmoon eastmoon 1241 2013-01-29 19:28 file_test.c
-rw------- 1 eastmoon eastmoon 12288 2013-01-29 19:28 .file.txt.swp
-rw-r--r-- 1 eastmoon eastmoon  233 2013-01-29 19:27 Makefile

3、  获取本地时间

代码：

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<time.h>
 
intmain(int argc, char *argv[])
{
    struct tm *ptr;
    time_t lt;
 
    //get current time
    lt = time(NULL);
 
    //turn to the native time
    ptr = localtime(<);
 
    //print the time as native time
    printf("%s\n", asctime(ptr));
 
    printf("%s\n", ctime(<));
 
    return 0;
}

Makefile

CC =gcc
 
CURTDIR= $(shell pwd)
TARGET= time
 
%.o:%.c
       $(CC) -c $(EXTRAFLAGS) $< -o $@
%.o:%.S
       $(CC) -c $(EXTRAFLAGS) $< -o $@
 
.PHONY:all clean
 
$(TARGET):$(TARGET).o
       $(CC) -o $@ $^
 
clean:
       rm -rf $(TARGET) $(TARGET).o

运行结果：

eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.7$make
gcc-c  time.c -o time.o
gcc  -o time time.o
 
eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.7$ls
Makefile  time time.c  time.o
 
eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.7$./time
TueJan 29 19:45:46 2013
 
TueJan 29 19:45:46 2013