posix IPC shared_memory一例

#include <sys/types.h> #include <stdio.h> #include <unistd.h> int value = 5; int main(void) { pid_t pid; pid = fork(); if (pid == 0) { value += 15; } else if (pid > 0) { wait(NULL); printf("PARENT: value = %d", value); exit(0); } }

输出PARENT: value =  5                 //              (各个进程有独立存储空间)

通过shared_memory解决数据共享 实现进程间通讯 代码稍作修改如下：

#include <sys/types.h> #include <sys/shm.h> #include <sys/stat.h> #include <stdio.h> #include <unistd.h> int value = 5; int main(void) { pid_t pid; int segment_id; char* shared_memory; const int size = 4096; segment_id = shmget(IPC_PRIVATE, size, S_IRUSR|S_IWUSR); shared_memory = (char*)shmat(segment_id, NULL, 0); pid = fork(); if (pid == 0) { value += 15; sprintf(shared_memory, "%d", value); } else if (pid > 0) { wait(NULL); printf("PARENT: value = %s\n", shared_memory); exit(0); } return 0; }

输出PARENT: value =  20