嵌c基础Linux源代码

1、arm嵌入式linux系统开发详解.linuxx应用程序开发详解源代码#include <stdio.h>int main()printf (z，hello world!n，z);return 0;/从文件读写成块数据ttinclude <stdio. h>int main()int buf1024二0;int p;file *fp = fopen(". /blk_file. dat", "rb+)； if (null二fp)return t;fwrite(buf, sizeof (int), 1024, fp) ;/ 把 1024个数据块

2、写入文件流fp,每个数据块4个字节/*修改buf的数据，供读取后比较*/for (i二0;i<16;i+)bufi二-1;p = &buf0; /设置指针p指向buf,供从文件读取数据使用 fread(p, sizeof (int), 1024, fp) ;/ 从文件读取 1024个数据块到buf,每个数据块4个字节/*打印从文件读取的二进制数据*/for (i=0;i<1024;i+) printf (，zbuf %d = %dn, i, buf i);fclose(fp) ;/最后别忘了关闭文件return 0;ttinclude <stdio.h> int

3、 main()file *fp = null;char *buf3 = 用"this is first line! n，z, "second line!n，z,"ok, the last line!nz，; char tmpbuf364, *p;用int i;/定义文件指针/定义三个字符串，供写入文件使/定义字符串缓存，供读取文件使fp = fopen(，zchap7_demo. dat，z, ，zrb+，z) ;/ 使用读写方式打开文件，并且把文件长度置0if (null二二fp) printf ("error to open file!n，z);re

4、turn t;/把三个字符串写入文件for (i=0;i<3;i+)fputs(bufi, fp);fseek(fp, 0, seek_set) ;/把文件指针设置到文件开头，相当于 rew in d(fp)/从文件读取三个字符串到缓存for (i=0;i<3;i+) p = tmpbufi;fgets(p, 64, fp);printfr%s p);打印刚读取出来的字符串到屏幕fclose (fp);/别忘记关闭文件return 0;/ c_memory_te s t c#include <stdio. h>sinclude <stdlib. h>int

5、main()char *p_strl, *p_str2;/定义两个char*指针/*使用malloc ()函数分配内存*/p_strl 二(char*)malloc(32);if (null=p_strl) /检查内存分配是否成功printf (，zalloc p strl memory error!n，z); return t;/*使用calloc ()函数分配内存*/p_str2 = (char*)calloc(32, sizeof(char);if (null二二p_str2) /检查内存是否分配成功printf (z，alloc p_str2 memory error!nz，); fr

6、ee(p_strl) ;/注意，这里需耍释放p_strl占用的内存return t;strcpy(p_strl, "this is a simple sentenee.)；/p_strl写入一个字符串strcpy(p_str2, p strl) ;/ p_str2写入与p_strl相同的字符串/*打印p_strl的结果*/printf (，zp_strl by malloc () :n，z);printf(p strl address: ox%. 8xp strl);/ p strl的内刼也址printf (，zp_strl: %s (%d chars) n，z, p_strl, s

7、trlcn(p_strl) ;/p_strl的内容/*打印p_str2的结果*/printf czp_str2 by cal loc () : n)；printf (，zp_str2 address: ox% 8xrt, p_str2) ;/ p_str2的内存地址printf (，zp_str2: %s (%d chars) n，/, p_str2, strlen(p_str2) ;/p_str2的内容/*为p_strl重新分配内存(减小)*/p_strl = (char*)realloc (p_strl, 16);if (null=p_strl) /检查内存分配结果printf (，zre

8、alloc p strl memory error!n)； free(p_str2) ;/注意，需要释放p_str2占用的内存return -1;p_strl15二0' ;/写字符串结束符/*为p_str2重新分配内存(增大)*/p_str2 二(char*)realloc(p_str2, 128);if (nui丄二二p_str2) /检查内存分配结果printf (z，realloc p_str2 memory error!nz，);free(p_strl) ;/注意，需耍释放p_strl占用的内存return t;strcat (p_str2, "the second

9、sentence in extra memory after realloced!，z);/*打印p_strl的结果*/printf(p strl after reallocedn)；printf (，zp_strl address: ox% 8xrt, p_strl) ;/ p_strl的内存地址printf (，zp_strl: %s (%d chars) n，/, p strl, strlen(p strl) ;/p_strl的内容/*打印p_str2的结果*/printf (，zp_str2 after realloced:n)；printf (，zp_str2 address: ox

10、%. 8xrt, p_str2) ;/ p_str2的内存地址printf czp_str2: %s (%d chars)n，p_str2, strlen(p_str2);/p_str2的内容/*注意，最后要释放占用的内存*/free (p strl) ;/ 释放p strl 占用的内存frcc(p_str2) ;/ 释放p_str2 占用的内存return 0;/*注意posix操作文件函数使用不同的头文件*/ #inelude <sys/types.h>#include <sys/stat. h>ftinclude <unistd. h>#include

11、 <fcntl. h> include <stdio. h>#inelude <crrno. h> extern int errno;int meiin()int fd;/注意，文件描述符是整型值char buf64二"this is a posix f订e!(line1)off_t currpos;fd = openc./posix. data", o_creat| o_rdwr| o_excl, s_1rwxu);打开一个不存在的文件，并创建文件，权施是用户可读写执行if (t二二fd) /检查文件打开是否成功switch (errn

12、o) case eexist:/文件已存在printf("file exist!n，z);break;default:/其他错误printf (，zopen file fail! n，z);break;return 0;writc(fd, buf, strlcn(buf) ;/ 把字符串写入文件curr_pos = lseek(fd, 0, seek_cur) ;/取得当前文件偏移量位置printf(f订e point at: %dcurrpos);iscckcfd, 0, seek.set) ;/把文件偏移量移动到文件开头strepy (buf, f订e pointer moved

13、! n，z);write(fd, buf, strlen(buf) ;/ 把新的数据写入文件filc_modc = fcntl(fd, f_getfl) ;/ 获取文件状态标记if (-1!=file_mode) switch (file_mode&0_accm0de) / 检查文件状态case o_rdonly:printf ("file mode is read 0nlyn，/);/存放在栈区char var_str二 “stringl”char *p_strl, *p_str2;/char *p_str3 = “string2” ;放在栈区static int var_

14、b = 100;/存放在栈区 存放在栈区/存放在已初始化数据区ptr_str3存全局静态数据，存放在已初始化区p_strl = (char*)malloc(1024); p_str2 = (char*)malloc(2048); free (pstrl);free(p_str2);/从堆区分配1024字节内存/从堆区分配2048字节内存break;case o_wronly:printf (，zfile mode is write 0nlyn/，); break;case o_rdwr:printf (z，file mode is read & writen); break;close

15、(fd);return 0;/test.cint g_var_a =0; char g_var_b;/存放在全局已初始化数据区/存放在bss区（未初始化全局变量）int main()int var_a;return 0;/ filenamegetenv. c -获取环境变量测试sinclude <stdio. h> #include <stdlib. h>char envpath = "path" char *env_value 二 null;/打算获取的环境变量名称/环境变量值cnv_valuc = gctcnv (cnv_path) ; /使用系

16、统函数获取指定环境变量 if (null=env_value)/检查是否获取到变量的值printf (/znot found!n，z);printf cget env path:n%s，z, env value) ; / 输出path环境变量的值 return 0;ttincludesys/types. h>include <unistd. h> #inelude <stdio. h> ttinclude <stdlib.h> int inainopid_t pid;pid = forko ;/创建进程if (t二二pid) /创建进程失败printf

17、 ("error to create new process!n)； rcturn 0;else if (pid=0) / 子进程printf(child process!n)； else /父进程printf (，zparent process! child process id: %dpid);return 0;/ process_demo. c#inelude <sys/types.h> ttinclude <sys/stat. h> #inelude <unistd.h sinclude <stdio. h> #include <

18、;stdlib. h>pidt pid, pidwait; int fd2;char buff64, *cmd 二"exit"/创建管道/子进程/关闭写操作if (pipe(fd) perror (，zcreate pipe fail!，z); return 0;pid = fork();if (-l=pid) perror (，zcreate process fail!，z);return 0; else if (0=pid) close(fdl);printf (，zwait command from parent! n，z); while(l) read (fd

19、o> buff, 64);if (0=strcmp(buff, cmd) printf("recv command ok!n)； close(fd0);exit (0); else /父进程printf (''parent process! child process id: %drt, pid); close(fd0) ;/关闭读操作sleep(2);printf("send command to child processrt);write(fdl, cmd, strlen(cmd)+1) ;/ 写入命令close(fdl);return 0;tt

20、include <sys/typesh> #include <unistdh> #inelude <stdio. h> ttinclude <stdlib. h> include <string. h>int fd2;pidt pid;char buf 64二，t，m parent process! n，z;/ 父进程要写入管道的信息char line64;if (0!二pipe(fd) /创建管道并检查结果pipe!n，z);fprintf(stderr, "fail to creatercturn 0;pid 二 for

21、k() ;/ 创建进程if (pid<0) fprintf (stderr, z，fail to create process! n，z);return 0; else if (0=pid) close(fd0);管道写入数据writc(fdl, buf, strlcn(buf); close(fdl); else close(fdl);管道读取数据 rcad(fd0, line, 64);printf(z，data from parent: %s", close(fd0);/父进程/关闭读管道，使得父进程只能向/写数据到管道/关闭写管道/子进程/关闭写管道，使得子进程只能从/

22、从管道读取数据 line);/关闭读管道rcturn 0;itinclude <stdio. h>jtincludc <stdlib. h>ttinclude <unistd. h>void bye (void)/退出时回调的函数printf (，zthat was all, folksrt);printf ("this should called first!n，z);int main() long a;i二atexit(bye);/设置退岀冋调函数并检查返冋结果if (i != 0) fprintf(stderr,nnot set exit f

23、unction byen)；return exit_failure;i = atcxit(bycl);/设置退岀回调函数并检查返回结果if (i!=0) fprintf (stderr, "cannot set exit function byeln");return exit_failure;return ex1t_success;include <sys/typesh> ttinclude <unistd. h> include <stdio. h>#inelude <stdlib.h>int ni3in()pidt pi

24、d, pidwait; int status;pid = fork();if (-l=pid) /创建子进程/检查是否创建成功printf (，zerror to createnew process!n");return 0;else if (pid=0) printf (z，child process! n); else /子进程/父进程printf (，zparent process! child process id: %dpid);pid_wai t 二 waitpid(pid, &status, 0) ;/ 等待指定进程号的子进printf (，zchild pro

25、cess %d returned!n，z, pid wait); "rcturn 0;#include <pthread h> #inelude <stdio. h> ttinclude <stdlib. h>void* thread_func(void *arg) "int *val = arg;printf("hi, i'm a thread!n，z);if (null!=arg) 印参数内容wh i1e (1)printf (，zargument set: %drt, *val);/线程函数/如果参数不为空，打in

26、t main()pthread_t tid; int targ = 100;值/线程1d/给线程传入的参数if (pthrcad_crcatc(&tid, mull, thrcad_func, &t_arg)/ 创建线程perror (''fail to create thread，z);sleep(l);执行printf (z，main thread!n); pthread cancel(tid);/睡眠1秒，等待线程/取消线程return 0;ttincludepthread h> itinclude <stdio. h>sinclude

27、<stdlib.h>void* thread_func(void *arg) "int *val 二 arg;printf("hi, i'm a thread!n，z);if (null!=arg)参数内容printf (argument set: %dn/z, *val);/线程函数/如果参数不为空，打卬int main()ptbread_t tid;int t_arg 二 100;/线程id/给线程传入的参数值if (pthread create(&tid, null, thread func, &t arg)/ 创建线程perror

28、(/zfail to create thread");slccp(l);printf("main thread!n)；/睡眠1秒，等待线程执行return 0;/ pthread_demo< c #include <pthread. h> #inelude <unistd.h sinclude <stdio. h> #include <stdlib. h>/ mid线程声明/ tcrni线程声明/存放线程idvoid* mid_tbread(void *arg); void* tcrm_thrcad(void *arg);in

29、t main()ptbread_t mi d_ti d, term_ti d;if (pthread_create(&mid_tid, null, mid_thread, null) / 创建mid线程perror (/zcreate mid thread error!/z);return 0;if (pthread create(feterm tid, null, term thread, (void*)&inid_tbread) /创建term线程pcrror ('"crcatc term thrcad fail! n)；return 0;if (pthr

30、ead join(mid tid, null) / 等待mid线程结束pcrror (，zwait mid thread error!，z);return 0;if (pthread join(term tid, null) / 等待term线程结束pcrror (，zwait term thrcad error!z，);return 0;return 0;void* mid thread (void *arg)/ mid线程定义 "int times 二 0;printf(mid thread created!n)；while(l) /不断打印等待的次数，间隔2秒printf (/

31、zwaitting term thread %d times!n，times);sleep (2);times+;/ tenn线程定义/如果线程id合法，结束线程void* term thread (void *arg) "pthrcad_t *tid;printf(z，term thread created!n)； sleep(2);if (null!=arg) t i d = (pthread_t*)arg; pthrcad_canccl(*tid);/ shm_read> c -> gcc -o r shm_read. c#inelude <sys/ipc.

32、h>#inelude <sys/shm. h>#inelude <sys/typcs. h>ftinclude <unistd. h>int main()int shmid;/定义共享内存idchar *ptr;shmid = shmget(0x90, 1024, shm_w|shm_r| ipc_excl) ;/ 根据key获得共享内存idif (-l=shmid)perror(z，create share memory");ptr = shmat (shmid, 0, 0) ;/通过共享内存id获得共享内存地址if (void*)t二二p

33、tr) perror (z，get share memory'7);printf (/zstring in share memory: %sptr) ;/ 打印共享内存中的内容shmdt(ptr);return 0;/ shm_write. c -> gcc -o w shm_write. c #include <sys/ipc. h>#inelude <sys/shm. h>#includesys/types. h>#inelude <unistd. h int main()int shmid;/定义共享内存idchar *ptr;char

34、*shm_str = "string in a share memory;shmid 二 shmget (0x90, 1024, shm_w| shm_r | ipc_creat | ipc_excl); 创建 共享内存if (-l=shmid)perror(/zcreate share memory");/通过共享内存id获得共享内ptr = (char*)shmat(shmid, 0, 0); 存地址if (void*)-1 二二ptr)perror(/zget share memory");strcpy(ptr, shmstr); shmdt(ptr);/把

35、字符串写入共享内存return 0;/ echo_client - gcc -o c echo_clientc itinclude <sys/types. h> ttinclude <sys/socket. h>include <netinet/in.h>#include <arpa/inet. h> ttinclude <unistd. h>#include <stdio. h>#inelude <errno. h> ttdcfinc ehco_port 8080define max_command 5int

36、 main()int sock_fd;struct sockaddr_in serv_addr;char *buffmaxcommand二abc， def， "test", hello， "quit"char tmpbuf100;socklen_t len;int n, i;/* 创建socket */sock_fd 二 socket(af_tnet, sock_stream, 0);if(sock_fd二二t) perror(z，create socket error!，z);return 0; else pri ntf ("success

37、to create socket %dn，z, sock_fd);/*设置server地址结构*/bzero (&serv addr, si zeof(serv addr); 用的内存serv_addrsin_family = af_1net;型/初始化结构占/设置地址传输层类serv addr. sin port 二 htons (ehco port);serv addr. sin addr. s_addr 二 htons(tnaddr any);/设置监听端口/设置服务器地bzero(&(serv_addr sin_zero), 8);/*连接到服务端*/if (-1二二c

38、onnect(sockfd, (struct sockaddr*)&servaddr, sizcof(scrv_addr) perror ("connect() error!n);close (sock fd);return 0;printf ("success cormcct to server! n，z);/*发送并接收缓冲的数据*/for (i=0;i<max_c0mmand;i+) send(sock_fd, buff i, 100, 0);服务端n 二 recv(sock_fd, tmp_buf, 100, 0);收数据tmp_buf n二0'

39、; ;/给字符串添加结束标志printfczdata send: %s receive: %sn，buffi, 打印字符串/发送数据给/从服务端接tmp buf) ;/if (0=strncmp(tmp_buf, "quit", 4) 退岀命令/判断是否是break;close(sock fd);/关闭套接字return 0;/ echo_serv. c 一 gcc -o s echo_serv. c #include <sys/typesh>ftinclude sys/socket.h> #include <netinet/in. h> #i

40、nelude <arpa/inet.h> #include unistd.h> #inelude <stdio.h> sinclude <errno. h> ttdefine ehc0_p0rt 8080ttdefine max_cltent_num 10 int main()int sock_fd;struct sockaddr_in serv_addr; int clicntfd;struct sockaddr_in clientadd; char buff101;socklen_t len;int closing 二0;int n;/* 创建so

41、cket */ sock_fd 二 socket(af_inet, sock_stream, 0);if(sock_fd=-l) perror (，zcrcatc socket error!，z);return 0; else printf("success to create socket %dsock_fd);/*设置server地址结构*/初始化结构占/设置地址传输层类/设置监听端口bzero(&serv_addr, sizeof(serv_addr); 用的内存serv addr. sinfamily 二 af tnet;型 一一"serv_addr. si

42、n_port = htons (ehc0_p0rt);serv_addr. sin_addr. s_addr = htons (inaddr any) ;/ 设置服务器地bzero (&(serv_addr. sin_zero), 8);/*把地址和套接字绑定*/if (bind (sock fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)!= 0)printf(bind address fail! %dn，errno);close(sock_fd);return 0; else printf ("success

43、to bind address!n，z);/*设置套接字监听*/if(listen(sock_fd ,max_client_num) !二 0) perror(listen socket error!n)；close (sock_fd);return 0; else printf("success to listenn)；/*创建新连接对应的套接字*/len = sizeof (clientadd);clientfd 二 accept(sock_fd, (struct sockaddr*)&clientadd, &len); if (clientfd<=0) p

44、error ("accept() error!n)； close (sock_fd);return 0;/*接收用户发來的数据*/ while(n = reev(clientfd, buff, 100, 0 ) > 0) buffn =，0, ; /给字符串加入结束符/打印字符串七printf("number of receive bytes 二 %d data 二 %sn, buff); fflush(stdout);send(clientfd, buff, n, 0) ;/发送字符串内容给客户端if(strncmp(buff, "quit",

45、4) = 0)/ 判断是否是退出命令break;closc(clicntfd) ;/关闭新建的连接close(sock_fd) ;/关闭服务端监听的socketreturn 0;/ time_client. c - gcc -o c time_client. c ttinclude <sys/types. h>include <sys/socket. h>tfinclude <netinet/in.h> #include <arpa/inet. h> #inelude <unistd.h> include <stdio.h>

46、; #inelude <crrno.h>define time_port 9090 #define data_size 256int mairioint sockfd; struct sockaddr_in serv; int servlen, n;char buffdata_size;sock_fd = socket (af_inet, sock_dgram, 0); if (sock_fd<=0) /创建套接字perror(create socket error!"); return 0;perror(/zcreate socket");/*设置服务端

47、ip和端口 */ scrv. sin_feiniily=af_inet; serv.sin_port=htons(t1me_port); serv.sin addr. s_addr=inaddr_any; servlen 二sizeof(serv);/监听端口/本机ip/*请求时间*/strcpy(buff, "time");if (t 二二 send to (sockfd, buff, sizeof (buff), servlen) /发送请求perror ("send data，z);close(sock_fd);0, (struet sockaddr*)&a

48、mp;serv,return 0;printf(send time requestn)；n 二 reevfrom(sock_fd, buff, sizeof (buff), &servlen) ;/接收返回0, (struet sockaddr*)&serv,if (n<=0) perror (/zrecv data!n)； close (sock fd);return 0;buff n二'0,;printf(time from server: %s， buff);/*退出连接*/strcpy(buff, "quit");if (-l=send

49、to(sock fd, buff, sizeof (buff), 0, (struct sockaddr*)&serv, servlen) pcrror (，zscnd data/z);close(sock_fd);return 0;printf(send quit commandn);close (sock_fd); return 0;/ time_serv. c - gcc -o s time_serv. c itinclude <sys/types. h> ttinclude <sys/socket. h>include <netinet/in.h&

50、gt;#include <arpa/inet. h> ttinclude <unistd. h>#include <stdio.h>#inelude <errno. h>#inelude <time. h>define t1me_port 9090define data_size 256int main()int sock_fd;struct sockaddrin local;struct sockaddr_in from;int fromlen, n;char buffdata_size;time_t cur_time;/建立套接字

51、sock_fd 二 socket(af_inet, sock_dgram, 0); if (sock fd<=0) perror(''create socket error!，z); return 0;perror(z/create socket");/*设置要绑定的ip和端口 */loca1. sin_family=af_inet;local. sin_port=htons(time port) ;/ 监听端口local, sin addr. s_addr=tnaddr_any;/本机/*绑定本机到套接字*/if (0!=bind(sock fd, (stru

52、ct sockaddr*)&1ocnl, sizeof(locnl) perror (/zbind socket error!/z);close(sock_fd);rctunn 0;printf(''bind socket");fromlen 二sizeof(from);printf (，zwaiting request from clicnt n)；while 仃)n 二 reevfrom(sock_fd, buff, sizeof (buff), 0, (struct sockaddr*)&from, &fromlcn) ; /接收数据if

53、 (n<=0) perror(z/recv data!n/z);close(sock_fd);return 0; buffn= 0' ;/设置字符串结束符printf (，zclient request: %sn", buff); 的字符串/打卬接收到if (0=strncmp(buff, "quit", 4) break;/判断是否退出if (0strncmp(buff, "time", 4) 吋间cur_timc = time(mull);/判断是否请求strepy (buff, asetime (gmtime(&cu

54、r_time); 间字符串sendto(sock_fd, buff, sizeof (buff), 0, (struct sockaddr*)&from, fromlen) ;/ 发送吋间给客户端/生成当前时/关闭套接字 close(sockfd); rcturn 0;/* at_test c - gcc o #inelude <stdio. h> ttinclude <stdlib. h> ttinclude <unistd h> ttinclude <sys/typesh> #include <sys/stat. h> include <fcntl. h> ttincludetermios h> ttinclude <errno. h> at_test at_test c */*标准输入输出定义*/ /*标准函数库定义*/ /*unix标准函数定义*/*文件控制定义*/ /*ppsix终端控制定义*/*错误号定义*/ttin