new file: CMakeLists.txt

 	new file:   include/head.h
 	new file:   src/main.c

Author: DataEraserC

c/fd/CMakeLists.txt

@@ -0,0 +1,5 @@
+CMAKE_MINIMUM_REQUIRED(VERSION 2.9)
+PROJECT(fd)
+INCLUDE_DIRECTORIES(./include)
+AUX_SOURCE_DIRECTORY(./src DIR_SRC)
+ADD_EXECUTABLE(./bin ${DIR_SRC})

c/fd/include/head.h

@@ -0,0 +1,6 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+

c/fd/src/main.c

@@ -0,0 +1,68 @@
+#include "../include/head.h"
+int main(){
+    char *path="file.txt";
+    int fd;
+    char buf[40],buf2[]="hello world";
+    int n,i;
+    if ((fd=open(path,O_RDWR))<0){
+        perror("open file failed");
+        return 1;
+    }
+    else
+    {
+        printf("open file successfully\n");
+    }
+
+    if ((n=read(fd,buf,20))<0){
+            perror("read failed");
+            return 1;
+    }
+    else
+    {
+        printf("output read data:\n");
+        printf("%s\n",buf);
+    }
+    if ((i=lseek(fd,11,SEEK_SET))<0){
+        perror("lseek error");
+        return 1;
+    }
+    else
+    {
+        if (write(fd,buf2,11)<0){
+            perror("write error");
+            return 1;
+        }
+        else
+        {
+            printf("write successfully\n");
+        }
+    }
+    close(fd);
+
+    if ((fd=open(path,O_RDWR))<0){
+        perror("open file failed");
+        return 1;
+    }
+    else
+    {
+        if ((n=read(fd,buf,40)<0))
+        {
+            perror("open file 2  failed");
+            return 1;
+        }
+        else
+        {
+            printf("read the changed data:\n");
+            printf("%s\n",buf);
+        }
+        if (close(fd)<0){
+            perror("close file failed");
+            return 1;
+        }
+        else
+        {
+            printf("goodbye\n");
+        }
+    }
+    return 0;
+}