嵌c基础Linux源代码

ARM 嵌入式嵌入式 Linux 系统开发详解系统开发详解 Linux c 应用程序开发详解应用程序开发详解 源代码源代码 include int main printf Hello World n return 0 从文件读写成块数据从文件读写成块数据 include int main int buf 1024 0 int p FILE fp fopen blk file dat rb if NULL fp return 1 fwrite buf sizeof int 1024 fp 把1024个数据块写 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 0 i 16 i buf i 1 p 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 buf d d n i buf i fclose fp 最后别忘了关闭文件 return 0 include int main FILE fp NULL 定义文件指针 char buf 3 定义三个字符串 供写入文件 使用 This is first line n Second Line n OK the last line n char tmp buf 3 64 p 定义字符串缓存 供读取文件 使用 int i fp fopen chap7 demo dat rb 使用读写方式打开文件 并且把文件长度置0 if NULL fp printf error to open file n return 1 把三个字符串写入文件 for i 0 i 3 i fputs buf i fp fseek fp 0 SEEK SET 把文件指针设置到文件开头 相当于rewind fp 从文件读取三个字符串到缓存 for i 0 i 3 i p tmp buf i fgets p 64 fp printf 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 test cc memory test c include include int main char p str1 p str2 定义两个char 指针 使用malloc 函数分配内存 p str1 char malloc 32 if NULL p str1 检查内存分配是否 成功 printf Alloc p str1 memory ERROR n return 1 使用calloc 函数分配内存 p str2 char calloc 32 sizeof char if NULL p str2 检查内存是否分配 成功 printf Alloc p str2 memory ERROR n free p str1 注意 这里需 要释放p str1占用的内存 return 1 strcpy p str1 This is a simple sentence p str1写入一个字符串 strcpy p str2 p str1 p str2写入 与p str1相同的字符串 打印p str1的结果 printf p str1 by malloc n printf p str1 address 0 x 8x n p str1 p str1 的内存地址 printf p str1 s d chars n p str1 strlen p str1 p str1的内容 打印p str2的结果 printf p str2 by calloc n printf p str2 address 0 x 8x n p str2 p str2 的内存地址 printf p str2 s d chars n p str2 strlen p str2 p str2的内容 为p str1重新分配内存 减小 p str1 char realloc p str1 16 if NULL p str1 检查内存分配结果 printf Realloc p str1 memory ERROR n free p str2 注意 需要释 放p str2占用的内存 return 1 p str1 15 0 写字符串结束 符 为p str2重新分配内存 增大 p str2 char realloc p str2 128 if NULL p str2 检查内存分配结果 printf Realloc p str2 memory ERROR n free p str1 注意 需要释 放p str1占用的内存 return 1 strcat p str2 The second sentence in extra memory after realloced 打印p str1的结果 printf p str1 after realloced n printf p str1 address 0 x 8x n p str1 p str1 的内存地址 printf p str1 s d chars n p str1 strlen p str1 p str1的内容 打印p str2的结果 printf p str2 after realloced n printf p str2 address 0 x 8x n p str2 p str2 的内存地址 printf p 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 str1 释放p str1占 用的内存 free p str2 释放p str2占 用的内存 return 0 注意注意POSIXPOSIX操作文件函数使用不同的头文件操作文件函数使用不同的头文件 include include include include include include extern int errno int main int fd 注意 文件描述符是整型值 char buf 64 this is a posix file line1 n off t curr pos fd open posix data O CREAT O RDWR O EXCL S IRWXU 打开一个不存在的文件 并创建文件 权限是用户可读写执行 if 1 fd 检查文件打开是否成功 switch errno case EEXIST 文件已存在 printf File exist n break default 其他错误 printf open file fail n break return 0 write fd buf strlen 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 File Point at d n curr pos lseek fd 0 SEEK SET 把文件偏移量移动到文件开头 strcpy buf File Pointer Moved n write fd buf strlen buf 把新的数据写入文件 file mode fcntl fd F GETFL 获取文件状态标记 if 1 file mode switch file mode break case O WRONLY printf file mode is WRITE ONLY n break case O RDWR printf file mode is READ break close fd return 0 test c test c int g var a 0 存放在全局已初始化数据区 char g var b 存放在BSS区 未初始化全局变量 int main int var a 存放在栈区 char var str string1 存放在栈区 char p str1 p str2 存放在栈区 char p str3 string2 存放在已初始化数据区 ptr str3存 放在栈区 static int var b 100 全局静态数据 存放在已初始化区 p str1 char malloc 1024 从堆区分配1024字节内存 p str2 char malloc 2048 从堆区分配2048字节内存 free p str1 free p str2 return 0 filenamefilename getenv cgetenv c 获取环境变量测试获取环境变量测试 include include int main char env path PATH 打算获取的环境变量名称 char env value NULL 环境变量值 env value getenv env path 使用系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 Not found n printf Get Env PATH n s env value 输出PATH环境变量的值 return 0 include include include include include include int main pid t pid pid fork 创建进程 if 1 pid 创建进程失败 printf Error to create new process n return 0 else if pid 0 子进程 printf Child process n else 父进程 printf Parent process Child process ID d n pid return 0 process demo cprocess demo c include include include include include int main pid t pid pid wait int fd 2 char buff 64 cmd exit if pipe fd 创建管道 perror Create pipe fail return 0 pid fork if 1 pid perror Create process fail return 0 else if 0 pid 子进程 close fd 1 关闭写操作 printf wait command from parent n while 1 read fd 0 buff 64 if 0 strcmp buff cmd printf recv command ok n close fd 0 exit 0 else 父进程 printf Parent process child process id d n pid close fd 0 关闭读操作 sleep 2 printf Send command to child process n write fd 1 cmd strlen cmd 1 写入命令 close fd 1 return 0 include include include include include include include int main int fd 2 pid t pid char buf 64 I m parent process n 父进程要写入管道的信 息 char line 64 if 0 pipe fd 创建管道并检查结果 fprintf stderr Fail to create pipe n return 0 pid fork 创建进程 if pid 0 fprintf stderr Fail to create process n return 0 else if 0 pid 父进程 close fd 0 关闭读管道 使得父进程只能 向管道写入数据 write fd 1 buf strlen buf 写数据到管道 close fd 1 关闭写管道 else 子进程 close fd 1 关闭写管道 使得子进程只能 从管道读取数据 read fd 0 line 64 从管道读取数据 printf DATA From Parent s line close fd 0 关闭读管道 return 0 include include include include void bye void 退出时回调的函数 printf That was all folks n void bye1 void 退出时回调的函数 printf This should called first n int main long a int i i atexit bye 设置退出回调函数并检查返回结果 if i 0 fprintf stderr cannot set exit function bye n return EXIT FAILURE i atexit bye1 设置退出回调函数并检查返回结果 if i 0 fprintf stderr cannot set exit function bye1 n return EXIT FAILURE return EXIT SUCCESS include include include include include include int main pid t pid pid wait int status pid fork 创建子进程 if 1 pid 检查是否创建成功 printf Error to create new process n return 0 else if pid 0 子进程 printf Child process n else 父进程 printf Parent process Child process ID d n pid pid wait waitpid pid 等待指定进程号的子进 程 printf Child process d returned n pid wait return 0 include include include include void thread func void arg 线程函数 int val arg printf Hi I m a thread n if NULL arg 如果参数不为空 打印参数内容 while 1 printf argument set d n val int main pthread t tid 线程ID int t arg 100 给线程传入的参数 值 if pthread create sleep 1 睡眠1秒 等待线程 执行 printf Main thread n pthread cancel tid 取消线程 return 0 include include include include void thread func void arg 线程函数 int val arg printf Hi I m a thread n if NULL arg 如果参数不为空 打印 参数内容 printf argument set d n val int main pthread t tid 线程ID int t arg 100 给线程传入的参数值 if pthread create sleep 1 睡眠1秒 等待线程执 行 printf Main thread n return 0 pthread demo cpthread demo c include include include include void mid thread void arg mid线程声明 void term thread void arg term线程声明 int main pthread t mid tid term tid 存放线程id if pthread create return 0 if pthread create return 0 if pthread join mid tid NULL 等待mid线程结束 perror wait mid thread error return 0 if pthread join term tid NULL 等待term线程结束 perror wait term thread error return 0 return 0 void mid thread void arg mid线程定义 int times 0 printf mid thread created n while 1 不断打印等待的次数 间隔2秒 printf waitting term thread d times n times sleep 2 times void term thread void arg term线程定义 pthread t tid printf term thread created n sleep 2 if NULL arg tid pthread t arg pthread cancel tid 如果线程id合法 结束线程 shm read cshm read c gccgcc o o r r shm read cshm read c include include include include int main int shmid 定义共享内存id char ptr shmid shmget 0 x90 1024 SHM W SHM R IPC EXCL 根据key获得 共享内存id if 1 shmid perror 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 1 ptr perror get share memory printf string in share memory s n ptr 打印共享内存 中的内容 shmdt ptr return 0 shm write cshm write c gccgcc o o w w shm write cshm write c include include include include int main int shmid 定义共享内存id char ptr char shm str string in a share memory shmid shmget 0 x90 1024 SHM W SHM R IPC CREAT IPC EXCL 创建 共享内存 if 1 shmid perror create share memory ptr char shmat shmid 0 0 通过共享内存id获得共享内 存地址 if void 1 ptr perror get share memory strcpy ptr shm str 把字符串写入共享内存 shmdt ptr return 0 echo clientecho client gccgcc o o c c echo client cecho client c include include include include include include include include include include include include define EHCO PORT 8080 define MAX COMMAND 5 int main int sock fd struct sockaddr in serv addr char buff MAX COMMAND abc def test hello quit char tmp buf 100 socklen t len int n i 创建socket sock fd socket AF INET SOCK STREAM 0 if sock fd 1 perror create socket error return 0 else printf Success to create socket d n sock fd 设置server地址结构 bzero 初始化结构占 用的内存 serv addr sin family AF INET 设置地址传输层类 型 serv addr sin port htons EHCO PORT 设置监听端口 serv addr sin addr s addr htons INADDR ANY 设置服务器地 址 bzero 连接到服务端 if 1 connect sock fd struct sockaddr close sock fd return 0 printf Success connect to server n 发送并接收缓冲的数据 for i 0 i MAX COMMAND i send sock fd buff i 100 0 发送数据给 服务端 n recv sock fd tmp buf 100 0 从服务端接 收数据 tmp buf n 0 给字符串添加结束标志 printf data send s receive s n buff i tmp buf 打印字符串 if 0 strncmp tmp buf quit 4 判断是否是 退出命令 break close sock fd 关闭套接字 return 0 echo serv cecho serv c gccgcc o o s s echo serv cecho serv c include include include include include include include include define EHCO PORT 8080 define MAX CLIENT NUM 10 int main int sock fd struct sockaddr in serv addr int clientfd struct sockaddr in clientAdd char buff 101 socklen t len int closing 0 int n 创建socket sock fd socket AF INET SOCK STREAM 0 if sock fd 1 perror create socket error return 0 else printf Success to create socket d n sock fd 设置server地址结构 bzero 初始化结构占 用的内存 serv addr sin family AF INET 设置地址传输层类 型 serv addr sin port htons EHCO PORT 设置监听端口 serv addr sin addr s addr htons INADDR ANY 设置服务器地 址 bzero 把地址和套接字绑定 if bind sock fd struct sockaddr close sock fd return 0 else printf Success to bind address n 设置套接字监听 if listen sock fd MAX CLIENT NUM 0 perror listen socket error n close sock fd return 0 else printf Success to listen n 创建新连接对应的套接字 len sizeof clientAdd clientfd accept sock fd struct sockaddr if clientfd 0 buff n 0 给字符串加入结束符 printf number of receive bytes d data s n n buff 打印字符串长度和内容 fflush stdout send clientfd buff n 0 发送字符串内容给客户端 if strncmp buff quit 4 0 判断是否是退出命令 break close clientfd 关闭新建的连接 close sock fd 关闭服务端监听的socket return 0 time client ctime client c gccgcc o o c c time client ctime client c include include include include include include include include include include define TIME PORT 9090 define DATA SIZE 256 int main int sock fd struct sockaddr in serv int servlen n char buff DATA SIZE sock fd socket AF INET SOCK DGRAM 0 创建套接字 if sock fd 0 perror create socket error return 0 perror Create socket 设置服务端IP和端口 serv sin family AF INET serv sin port htons TIME PORT 监听端口 serv sin addr s addr INADDR ANY 本机IP servlen sizeof serv 请求时间 strcpy buff time if 1 sendto sock fd buff sizeof buff 0 struct sockaddr close sock fd return 0 printf send time request n n recvfrom sock fd buff sizeof buff 0 struct sockaddr 接收返回 if n 0 perror recv data n close sock fd return 0 buff n 0 printf time from server s buff 退出连接 strcpy buff quit if 1 sendto sock fd buff sizeof buff 0 struct sockaddr close sock fd return 0 printf send quit command n close sock fd 关闭套接字 return 0 time serv ctime serv c gccgcc o o s s time serv ctime serv c include include include include include include include include include include include include include define TIME PORT 9090 define DATA SIZE 256 int main int sock fd struct sockaddr in local struct sockaddr in from int fromlen n char buff DATA SIZE time t cur time sock fd socket AF INET SOCK DGRAM 0 建立套接字 if sock fd 0 perror create socket error return 0 perror Create socket 设置要绑定的IP和端口 local sin family AF INET local sin port htons TIME PORT 监听端口 local sin addr s addr INADDR ANY 本机 绑定本机到套接字 if 0 bind sock fd struct sockaddr close sock fd return 0 printf Bind socket fromlen sizeof from printf waiting request from client n while 1 n recvfrom sock fd buff sizeof buff 0 struct sockaddr 接收数据 if n 0 perror recv data n close sock fd return 0 buff n 0 设置字符串结束符 printf client request s n buff 打印接收到 的字符串 if 0 strncmp buff quit 4 判断是否退出 break if 0 strncmp buff time 4 判断是否请求 时间 cur time time NULL strcpy buff asctime gmtime 生成当前时 间字符串 sendto sock fd buff sizeof buff 0 struct sockaddr 发送时间给客户端 close sock fd 关闭套接字 return 0 at test cat test c gccgcc o o at testat test at test cat test c include 标准输入输出定义 include 标准函数库定义 include include Unix Unix 标准函数定义标准函数定义 include include include include include include 文件控制定义文件控制定义 include include PPSIX PPSIX 终端控制定义终端控制定义 include include 错误号定义错误号定义 include include define STTY DEV dev ttyS0 define BUFF SIZE 512 int SetOption int fd struct termios opt 取得当前串口配置 tcgetattr fd tcflush fd TCIOFLUSH 设置波特率 19200bps cfsetispeed cfsetospeed 设置数据位 8位数据位 opt c cflag opt c cflag CS8 设置奇偶位 无奇偶校验 opt c cflag opt c iflag 设置停止位 1位停止位 opt c cflag 设置超时时间 15秒 opt c cc VTIME 150 opt c cc VMIN 0 设置写入设备 if 0 tcsetattr fd TCSANOW return 1 tcflush fd TCIOFLUSH return 0 int main int stty fd n iconv t cd char buffer BUFF SIZE char phone 20 8618912345678 定义手机号码 char sms number 20 8613800200500 定义短消息中心号码 char sms gb2312 140 工作愉快 定义短消息内容哦 char sms utf8 140 char sms in sms gb2312 char sms out sms utf8 int str len i tmp int gb2312 len utf8 len 打开串口设备 stty fd open STTY DEV O RDWR if 1 stty fd perror open device return 0 printf Open device success n 设置串口参数 if 0 SetOption stty fd close stty fd return 0 转换电话号 if phone 0 去掉号码开头的 for i 0 i strlen phone 1 i phone i phone i 1 phone i 0 str len strlen phone if strlen phone 2 0 如果号码长度是奇数 在后面加字符 F phone str len F phone str len 1 0 for i 0 i strlen phone i 2 把号码的奇偶位调换 tmp phone i phone i phone i 1 phone i 1 tmp 转换短消息中心号码 if sms number 0 去掉号码开头的 for i 0 i strlen sms number 1 i sms number i sms number i 1 sms number i 0 str len strlen sms number if strlen sms number 2 0 如果号码长度是奇数 在后面加字符 F sms number str len F sms number str len 1 0 for i 0 i utf 8 if 0 cd perror create iconv handle close stty fd return 0 gb2312 len strlen sms gb2312 输入字符串的长度 utf8 len 140 if 1 iconv cd close stty fd return 0 iconv close cd 设置使用PDU模式 strcpy buffer AT CMGF 0 n write stty fd buffer strlen buffer 写入配置命令 n read stty fd buffer BUFF SIZE if n 0 perror set pdu mode close stty fd return 0 if 0 strncmp buffer OK 2 判断命令是否执行 成功 perror set pdu mode close stty fd return 0 发送消息 sprintf buffer AT CMGS d n utf8 len 写入发送消息命令 write stty fd buffer strlen buffer write stty fd sms utf8 utf8 len 写入消息内容 printf Send message OK n close stty fd include 标准输入输出定义 include 标准函数库定义 include include Unix Unix 标准函数定义标准函数定义 include include include include include include 文件控制定义文件控制定义 include include PPSIX PPSIX 终端控制定义终端控制定义 include include 错误号定义错误号定义 int main int fd fd open dev ttyS0 O RDWR 使用读写方式打开串口 if 1 fd perror open ttyS0 return 0 printf Open ttyS0 OK n close fd 关闭串口 return 0 stty echo cstty echo c gccgcc o o stty echostty echo stty echo cstty echo c include 标准输入输出定义 include 标准函数库定义 include Unix 标准函数定义 include include include 文件控制定义 include PPSIX 终端控制定义 include 错误号定义 define STTY DEV dev ttyS0 define BUFF SIZE 512 int main int stty fd n char buffer BUFF SIZE struct termios opt 打开串口设备 stty fd open STTY DEV O RDWR if 1 stty fd perror open device return 0 printf Open device success waiting user input n 取得当前串口配置 tcgetattr stty fd tcflush stty fd TCIOFLUSH 设置波特率 19200bps cfsetispeed cfsetospeed 设置数据位 8位数据位 opt c cflag opt c cflag CS8 设置奇偶位 无奇偶校验 opt c cflag opt c iflag 设置停止位 1位停止位 opt c cflag 设置超时时间 15秒 opt c cc VTIME 150 opt c cc VMIN 0 设置写入设备 if 0 tcsetattr stty fd TCSANOW return 0 tcflush stty fd TCIOFLUSH 读取数据 直到接收到 quit 字符串退出 while 1 n read stty fd buffer BUFF SIZE if n 0 perror read data break buffer n 0 printf s buffer if 0 strncmp buffer quit 4 printf user send quit n break printf Program will exit n close stty fd FindDialog cppFindDialog cpp include include include include include include FindDialog h FindDialog FindDialog QWidget parent QDialog parent 构 造函数 Label new QLabel tr Find 创建文本标签控件 LineEdit new QLineEdit this 创建文本框控件 Label setBuddy LineEdit 绑定文本框控件和标签控件 CaseCB new QCheckBox tr Match 创建大小写 CheckBox BackwardCB new QCheckBox tr Search 创建搜 索方向CheckBox FindBtn new QPushButton tr 创建查找按钮 FindBtn setDefault true 设置查找按钮为激活状态 CloseBtn new QPushButton tr Close this 创建关闭按钮 connect LineEdit SIGNAL textChanged const QString 设置修改文本框事 件响应函数 connect FindBtn SIGNAL clicked this SLOT findClicked 设置单击查找按钮响应函数 connect CloseBtn SIGNAL clicked this SLOT close 设置单击关闭按钮响应函数 QHBoxLayout TopLeft new QHBoxLayout 创建列对齐的布局对象 TopLeft addWidget Label 添加文本标签控件到列对齐布局 TopLeft addWidget LineEdit 添加文本框控件到列对齐布局 QVBoxLayout Left new QVBoxLayout 创建行对齐的布局对象 Left addLayout TopLeft 添加列对齐布局到行对齐布局 Left addWidget CaseCB 添加大小写复选CheckBox控件到行布局 Left addWidget BackwardCB 添加前后向搜索CheckBox控件到行布局 QVBoxLayout Right new QVBoxLayout 创建右对齐的行布局对象 Right addWidget FindBtn 添加查找对象布局到右对齐布局 Right addWidget CloseBtn 添加关闭按钮到右对齐布局 Right addStretch 1 QHBoxLayout Main new QHBoxLayout this 创建行排列的主布局对 象 Main setMargin 11 Main setSpacing 4 设置控件留空距离 Main addLayout Left 添加左对齐布局 Main addLayout Right 添加右对齐布局 setLayout Main 设置应用程序使用主布局 setWindowTitle tr Find Dialog 设置窗体标题 void FindDialog FindClicked 查找按钮响应函数 QString text LineEdit text 从查找文本框读取要查找的文本 bool CaseSensitive CaseCB isChecked 获取是否需要大小 写敏感 if BackwardCB isChecked 判断向前还是向后搜索 FindPrev text CaseSensitive 向前搜索文本 else FindNext text CaseSensitive 向后搜索文本 void FindDialog EnableFindButton const QString class QLabel class QLineEdit class QPushButton class FindDialog public QDialog Q OBJECT public FindDialog QWidget parent 0 signals void FindNext const QString void FindPrev const QString private slots void FindClicked void EnableFindButton const QString private QLabel Label QLineEdit LineEdit QCheckBox CaseCB QCheckBox BackwardCB QPushButton FindBtn QPushButton CloseBtn endif FINDDIALOG H hello qt cpphello qt cpp include include int main int argc char argv QApplication a argc argv 定义应用对象 QPushButton hello Hello world 0 定义按钮对象 hello resize 100 30 设置按钮大小 a setMainWidget 设置主窗体控件 hello show 显示按钮 return a exec hello qt cpphello qt cpp include include int main int argc char argv QApplication a argc argv 定义应用程序对象 QLabel hello Hello World 0 定义标签 hello show 显示标签 return a