线程管理操作

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 SRC_FILE "./1.txt"
#define DST_FILE "./2.txt"
#define BUFFER_SIZE 4096struct copy_args {long start;long end;
};void* copy_thread(void* arg) {struct copy_args* str= (struct copy_args*)arg;// 打开源文件和目标文件FILE* src = fopen(SRC_FILE, "rb");if (!src) {perror("Source file open failed");pthread_exit(NULL);}FILE* dst = fopen(DST_FILE, "wb+"); if (!dst) {perror("Target file open failed");fclose(src);pthread_exit(NULL);}fseek(src, str->start, SEEK_SET);fseek(dst, str->start, SEEK_SET);char buffer[BUFFER_SIZE];long remain = str->end - str->start;while (remain > 0) {size_t read_size = fread(buffer, 1, remain > sizeof(buffer) ? sizeof(buffer) : remain, src);if (read_size <= 0) break;size_t write_size = fwrite(buffer, 1, read_size, dst);if (write_size != read_size) {fprintf(stderr, "Write error\n");break;}remain -= read_size;}fclose(src);fclose(dst);return NULL;
}int main() {//检查文件状态获取结果struct stat st;if (stat(SRC_FILE, &st) != 0) {perror("Source file not found");exit(EXIT_FAILURE);}// 正确处理奇数长度文件long half = (st.st_size % 2 == 0) ? st.st_size / 2 : (st.st_size + 1) / 2;pthread_t t1, t2;// 动态分配参数内存（避免栈内存失效）struct copy_args* str1 = malloc(sizeof(struct copy_args));struct copy_args* str2 = malloc(sizeof(struct copy_args));*str1 = (struct copy_args){0, half};*str2 = (struct copy_args){half, st.st_size};pthread_create(&t1, NULL, copy_thread, str1);pthread_create(&t2, NULL, copy_thread, str2);pthread_join(t1, NULL);pthread_join(t2, NULL);// 释放动态分配的内存free(str1);free(str2);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.h>sem_t semA, semB, semC;void* threadA(void* arg) {while(1) {sem_wait(&semA);printf("FIA ");sem_post(&semB);}
}void* threadB(void* arg) {while(1) {sem_wait(&semB);printf("FIB ");sem_post(&semC);}
}void* threadC(void* arg) {while(1) {sem_wait(&semC);printf("FIC\n");sem_post(&semA);}
}int main() {sem_init(&semA, 0, 1);sem_init(&semB, 0, 0);sem_init(&semC, 0, 0);pthread_t tA, tB, tC;pthread_create(&tA, NULL, threadA, NULL);pthread_create(&tB, NULL, threadB, NULL);pthread_create(&tC, NULL, threadC, NULL);pthread_join(tA, NULL);pthread_join(tB, NULL);pthread_join(tC, NULL);
}

#include <head.h>pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
int state = 0;void* threadA(void* arg) {while(1) {pthread_mutex_lock(&mutex);while(state != 0) pthread_cond_wait(&cond, &mutex);printf("FIA ");state = 1;pthread_cond_broadcast(&cond);pthread_mutex_unlock(&mutex);}
}void* threadB(void* arg) {while(1) {pthread_mutex_lock(&mutex);while(state != 1)pthread_cond_wait(&cond, &mutex);printf("FIB ");state = 2;pthread_cond_broadcast(&cond);pthread_mutex_unlock(&mutex);}
}void* threadC(void* arg) {while(1) {pthread_mutex_lock(&mutex);while(state != 2)pthread_cond_wait(&cond, &mutex);printf("FIC\n");state = 0;pthread_cond_broadcast(&cond);pthread_mutex_unlock(&mutex);}
}int main() {pthread_t tA, tB, tC;pthread_create(&tA, NULL, threadA, NULL);pthread_create(&tB, NULL, threadB, NULL);pthread_create(&tC, NULL, threadC, NULL);pthread_join(tA, NULL);pthread_join(tB, NULL);pthread_join(tC, NULL);
}