铁路建设标准网站,王璞网站开发实战,wordpress的源代码,做电影的网站赚什么钱1.创建两个线程#xff0c;分支线程1拷贝文件的前一部分#xff0c;分支线程2拷贝文件的后一部分
#include head.h#define BUFFER_SIZE 1024// 线程参数结构体#xff0c;包含文件名和文件偏移量
typedef struct {FILE *src_file;FILE *dest_file;long start_o…1.创建两个线程分支线程1拷贝文件的前一部分分支线程2拷贝文件的后一部分
#include head.h#define BUFFER_SIZE 1024// 线程参数结构体包含文件名和文件偏移量
typedef struct {FILE *src_file;FILE *dest_file;long start_offset;long length;
} ThreadArgs;// 线程1拷贝文件的前一部分
void *copyFirstPart(void *args) {ThreadArgs *thread_args (ThreadArgs *)args;FILE *src thread_args-src_file;FILE *dest thread_args-dest_file;long start_offset thread_args-start_offset;long length thread_args-length;// 分配缓冲区char buffer[BUFFER_SIZE];fseek(src, start_offset, SEEK_SET);long bytes_read 0;while (bytes_read length) {size_t read_size (length - bytes_read BUFFER_SIZE) ? (length - bytes_read) : BUFFER_SIZE;size_t read_count fread(buffer, 1, read_size, src);fwrite(buffer, 1, read_count, dest);bytes_read read_count;}printf(Thread 1 finished copying the first part.\n);return NULL;
}// 线程2拷贝文件的后一部分
void *copySecondPart(void *args) {ThreadArgs *thread_args (ThreadArgs *)args;FILE *src thread_args-src_file;FILE *dest thread_args-dest_file;long start_offset thread_args-start_offset;long length thread_args-length;// 分配缓冲区char buffer[BUFFER_SIZE];fseek(src, start_offset, SEEK_SET);long bytes_read 0;while (bytes_read length) {size_t read_size (length - bytes_read BUFFER_SIZE) ? (length - bytes_read) : BUFFER_SIZE;size_t read_count fread(buffer, 1, read_size, src);fwrite(buffer, 1, read_count, dest);bytes_read read_count;}printf(Thread 2 finished copying the second part.\n);return NULL;
}int main() {FILE *src_file fopen(head.h, rb);if (src_file NULL) {perror(Error opening source file);return 1;}// 获取源文件的大小fseek(src_file, 0, SEEK_END);long file_size ftell(src_file);fseek(src_file, 0, SEEK_SET);// 创建两个目标文件FILE *dest_file1 fopen(part1.h, wb);FILE *dest_file2 fopen(part2.h, wb);if (dest_file1 NULL || dest_file2 NULL) {perror(Error opening destination file);fclose(src_file);return 1;}// 创建线程pthread_t thread1, thread2;// 设置线程参数ThreadArgs args1 {src_file, dest_file1, 0, file_size / 2};ThreadArgs args2 {src_file, dest_file2, file_size / 2, file_size - file_size / 2};// 创建两个线程分别拷贝前后部分pthread_create(thread1, NULL, copyFirstPart, args1);pthread_create(thread2, NULL, copySecondPart, args2);// 等待线程完成pthread_join(thread1, NULL);pthread_join(thread2, NULL);// 关闭文件fclose(src_file);fclose(dest_file1);fclose(dest_file2);printf(File copy completed.\n);return 0;
} 2.创建3个线程线程A打印A线程B打印B线程C打印C要求重复打印顺序ABC (分别使用信号量和条件变量实现)
#include head.hsem_t semA, semB, semC; // 信号量A, B, C// 线程A打印A
void* printA(void* arg) {while (1) {sem_wait(semA); // 等待信号量Aprintf(A\n);sleep(1);sem_post(semB); // 释放信号量B通知线程B执行}return NULL;
}// 线程B打印B
void* printB(void* arg) {while (1) {sem_wait(semB); // 等待信号量Bprintf(B\n);sleep(1);sem_post(semC); // 释放信号量C通知线程C执行}return NULL;
}// 线程C打印C
void* printC(void* arg) {while (1) {sem_wait(semC); // 等待信号量C printf(C\n);sleep(1);sem_post(semA); // 释放信号量A通知线程A执行}return NULL;
}int main() {// 初始化信号量sem_init(semA, 0, 1); // 初始化信号量A为1线程A先执行sem_init(semB, 0, 0); // 初始化信号量B为0线程B等待线程Asem_init(semC, 0, 0); // 初始化信号量C为0线程C等待线程B// 创建线程pthread_t threadA, threadB, threadC;pthread_create(threadA, NULL, printA, NULL);pthread_create(threadB, NULL, printB, NULL);pthread_create(threadC, NULL, printC, NULL);// 等待线程结束实际上永远不会结束因为是无限循环pthread_join(threadA, NULL);pthread_join(threadB, NULL);pthread_join(threadC, NULL);// 销毁信号量sem_destroy(semA);sem_destroy(semB);sem_destroy(semC);return 0;
}#include head.h// 定义条件变量和互斥锁
pthread_cond_t cond PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex PTHREAD_MUTEX_INITIALIZER;// 用于控制线程执行的变量
int current_thread 0; // 0: A, 1: B, 2: C// 线程 A
void* print_A(void* arg) {while (1) {pthread_mutex_lock(mutex);while (current_thread ! 0) {pthread_cond_wait(cond, mutex); // 等待轮到线程 A}sleep(1);printf(A\n); // 打印 Afflush(stdout); // 刷新输出缓冲区current_thread 1; // 切换到线程 Bpthread_cond_broadcast(cond); // 唤醒其他线程pthread_mutex_unlock(mutex);}return NULL;
}// 线程 B
void* print_B(void* arg) {while (1) {pthread_mutex_lock(mutex);while (current_thread ! 1) {pthread_cond_wait(cond, mutex); // 等待轮到线程 B} sleep(1);printf(B\n); // 打印 Bfflush(stdout); // 刷新输出缓冲区current_thread 2; // 切换到线程 Cpthread_cond_broadcast(cond); // 唤醒其他线程pthread_mutex_unlock(mutex);}return NULL;
}// 线程 C
void* print_C(void* arg) {while (1) {pthread_mutex_lock(mutex);while (current_thread ! 2) {pthread_cond_wait(cond, mutex); // 等待轮到线程 C}sleep(1);printf(C\n); // 打印 Cfflush(stdout); // 刷新输出缓冲区current_thread 0; // 切换到线程 Apthread_cond_broadcast(cond); // 唤醒其他线程pthread_mutex_unlock(mutex);}return NULL;
}int main() {pthread_t thread_A, thread_B, thread_C;// 创建线程pthread_create(thread_A, NULL, print_A, NULL);pthread_create(thread_B, NULL, print_B, NULL);pthread_create(thread_C, NULL, print_C, NULL);// 等待线程结束pthread_join(thread_A, NULL);pthread_join(thread_B, NULL);pthread_join(thread_C, NULL);return 0;
}
