Work with cainiao to go deep into the file programming of the National embedded experiment

1. File Creation

Code:

#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 

 

Running result:

Eastmoon @ eastmoon-Virtual-machine :~ /Work/guoqian/1/1.5 $ makegcc-C file_create.c-ofile_create.ogcc-O file_createfile_create.o eastmoon @ eastmoon-Virtual-machine :~ /Work/guoqian/1/1.5 $ lsfile_create file_create.c file_create.o makefile eastmoon @ eastmoon-Virtual-machine :~ /Work/guoqian/1/1.5 $./file_create file_crecreate file file_re success! Eastmoon @ eastmoon-Virtual-machine :~ /Work/guoqian/1/1.5 $ ll have been interrupted? 40drwxr-xr-x 2 eastmoon 4096. /drwxr-XR-x 8 eastmoon 4096 .. /-RW-r -- 1 eastmoon 0 2013-01-29 file_cre-rwxr-xr-x 1 eastmoon 7232 file_create *-RW-r -- 1 eastmoon 571 file_create.c-rw-r -- r -- 1 eastmoon 1204 file_create.o-rw ------- 1 eastmoon 12288 .file.txt. SWP-RW-r -- 1 eastmoon 237 makefile

 

2. file copy

Code:

#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 

 

Running result:

Eastmoon @ eastmoon-Virtual-machine :~ /Work/guoqian/1/1.5 $ makegcc-C file_cp.c-O file_cp.ogcc-O file_cp file_cp.o eastmoon @ eastmoon-Virtual-machine :~ /Work/guoqian/1/1.5 $./file_cp file_cp.c file_test.cfrom file size is 1241 eastmoon @ eastmoon-Virtual-machine :~ /Work/guoqian/1/1.5 $ ll have been interrupted? 44drwxr-xr-x 2 eastmoon 4096. /drwxr-XR-x 7 eastmoon 4096 .. /-rwxr-XR-x 1 eastmoon 7472 file_cp *-RW-r -- 1 eastmoon 1241 file_cp.c-rw-r -- r -- 1 eastmoon 1868 file_cp.o-rw-r -- r -- 1 eastmoon 1241 file_test.c-rw ------- 1 eastmoon 12288 .file.txt. SWP-RW-r -- 1 eastmoon 233 makefile

 

 

3. Obtain the local time

Code:

#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 

 

Running result:

eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.7$makegcc-c  time.c -o time.ogcc  -o time time.o eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.7$lsMakefile  time time.c  time.o eastmoon@eastmoon-virtual-machine:~/work/guoqian/1/1.7$./timeTueJan 29 19:45:46 2013 TueJan 29 19:45:46 2013