利用工作之余為小伙伴寫了份作業，關于進程間通信的。題目如下：
“父進程從鍵盤上接受1000個數據，對其求和sum1，子進程對這1000個數平方和sum2，結果傳給父進程，父進程將sum1+sum2后，打印結果。”
要求：用大小為10的共享區傳遞1000個數據；子進程用消息機制將sum2傳給父進程。
主要利用共享內存實現進程間通信，使用管道實現進程間競爭關系，FreeBSD下測試通過。代碼如下：時間有限，有可能有些不足，希望高手給予指點。
#include <stdio.h>#include <string.h>#include <stdlib.h>#include <sys/shm.h>#include <signal.h>const int key = 0x12345678;static int pfd1[2], pfd2[2];#define SHM_LEN (10*1024)#define VAL_NUM 5int init_shm() { int shmid = -1; shmid = shmget((key_t)key, SHM_LEN, 0666 | IPC_CREAT); if (shmid < 0) { printf("shmget failed!/n"); exit(-1); } return shmid;}void cancel_shm(int shmid) { if (shmctl(shmid, IPC_RMID, 0) == -1) { printf("shmctl failed!/n"); exit(-1); } printf("cancel_shm successfully!/n");}void *shm_get(int shmid) { void *mem = NULL; mem = shmat(shmid, 0, 0); if (mem == (void *)-1) { printf("shmat failed!/n"); exit(-1); } return mem;}int get_val(int *val, int num) { int i; for (i = 0; i < num; i++) { printf("please input a num:"); scanf("%d", val + i); }}void show_val (int *val, int num) { int i; for (i = 0; i < num; i++) { printf("%d/t", *(val + i)); } printf("/n");}int add_val (int *val, int num) { int result = 0; int i; for (i = 0; i < num; i++) { result += *(val + i); } return result;}int square_val (int *val, int num) { int result = 0; int i, tmp; for (i = 0; i < num; i++) { tmp = *(val + i); result += (tmp * tmp); } return result;}void TELL_WAIT (void) { if (pipe(pfd1) < 0 || pipe(pfd2) < 0) { printf("pipe error!/n"); exit(-1); }}void TELL_PARENT (pid_t pid) { if (write(pfd2[1], "c", 1) != 1) { printf("write error!/n"); exit(-1); }}void WAIT_PARENT (void) { char c; if (read(pfd1[0], &c, 1) != 1) { printf("read error!/n"); exit(-1); }}void TELL_CHILD (pid_t pid) { if (write(pfd1[1], "p", 1) != 1) { printf("write error!/n"); exit(-1); }}void WAIT_CHILD (void) { char c; if (read(pfd2[0], &c, 1) != 1) { printf("read error!/n"); exit(-1); }}int main(int argc, char *argv[]) { void *mem = NULL; int shmid = -1; pid_t pid = -1; int val[VAL_NUM]; int result = 0; shmid = init_shm(); TELL_WAIT(); if ((pid = fork()) < 0) { //error printf("fork error!/n"); exit(-1); } else if (pid == 0) { //child int result = 0; WAIT_PARENT(); mem = shm_get(shmid); //get share memery memcpy(val, mem, sizeof(int) * VAL_NUM); result = square_val(val, VAL_NUM); *(int *)((void *)mem + SHM_LEN - 4) = result; TELL_PARENT(pid); exit(1); } else { //parent int child_result = 0; mem = shm_get(shmid); //get share memery get_val(val, VAL_NUM); //get user input memcpy(mem, val, sizeof(int) * VAL_NUM); //copy user input to share memery TELL_CHILD(pid); result = add_val(val, VAL_NUM); WAIT_CHILD(); child_result = *(int *)((void *)mem + SHM_LEN - 4); printf("result:%d, child_result:%d, all:%d/n", result, child_result, result + child_result); } cancel_shm(shmid); return 0;} 以上就是本文的全部內容，希望對大家的學習有所幫助。
