The exercises in the third chapter of the fourth edition of Linux programming

1, P103

A directory scanner.

 #include <stdio.h> #include <dirent.h> #include <sys/stat.h>int    Isadir (char* path); Determine if the path is a directory type void Printdirs (char* path,int depth)//recursively traverse the print file with the directory name {dir* dir=opendir (path); struct dirent* Dirents;chdir ( Path), while (Dirents=readdir (dir)) {if (Isadir (dirents->d_name)) {if (strcmp (".", Dirents->d_name) ==0| | strcmp ("..", Dirents->d_name) ==0) continue;printf ("%*s%s/\ n", depth, "", Dirents->d_name);p Rintdirs (dirents- >d_name,depth+1);} elseprintf ("%*s%s/\ n", depth, "", Dirents->d_name);} ChDir (".."); Closedir (dir);} int Isadir (char* path) {struct stat statbuff;//printf ("%s", path); Lstat (Path,&statbuff); if (S_isdir (statbuff.st_ mode) {return 1;} return 0;}          int main (int argc,char* argv[]) {/* char* path[1023];gets (path);     Pathchdir (Path) entered by the user in the program, */char* path= "."; Use the program's parameters when Pathif (argc >=2) {path = argv[1];} if (Isadir (path) ==1) {printdirs (path,0);p error ("Wrong::"); return 1;} printf ("Path is not a dir"); return 1;} 

2, P112

Use the MMAP function program to modify the contents of the file, map the file to memory, and change it as an array!

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <sys/ Mman.h> #define RECORDNUM (a) struct       record//recording structure {int integ;char string[15];} Record;int creatfile (char* file) {struct Record R; file* fp=fopen (file, "w+"); int i=0;for (; i<50;i++) {r.integ=i;memset (r.string,0,15);      sprintf (r.string, "record-%d", I);   format string input into R.string fwrite (&r,sizeof (R), 1,FP);} Fclose (FP);} void Memomap (char* file) {struct record record,*r;int f=open (FILE,O_RDWR); r= (struct record *) mmap (0, Recordnum*sizeof ( struct Record), prot_read| Prot_write, map_shared, f,0);   Memory-mapped functions r[20].integ=100;sprintf (r[20].string, "record-%d", R[20].integ), Msync ((void*) r,recordnum*sizeof (Record), Ms_sync);               Save the modification of the memory segment back to the file Munmap ((void*) r,recordnum*sizeof (RECORD));//Free memory segment Close (f); return;} int main (int argc,char* argv[]) {creatfile ("records.date"); Memomap ("records.date"); return 1;}

The exercises in the third chapter of the fourth edition of Linux programming