有關msg1.cpp如何進入第二個循環的任何建議?我編譯並執行這兩個程序並且不會收到錯誤消息。當我編譯並執行msg2.cpp時,它會提示用戶輸入一些文本。當用戶輸入文本時msg1.cpp顯示用戶輸入。問題是msg1.cpp不會提示用戶'輸入一些文本',因爲它沒有進入循環。 64行是程序進入循環的時候。程序應該工作,因爲運行不再等於零,它等於一! 不會發布msg2.cpp源代碼,因爲msg2.cpp與我的問題無關。程序未進入第二循環?
//msg1.cpp
/* Here's the receiver program. */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#define MAX_TEXT 512
using namespace std;
struct my_msg_st {
long int my_msg_type;
char some_text[BUFSIZ];
//char some_text[MAX_TEXT];
};
int main()
{
int running = 1;
int msgid;
struct my_msg_st some_data;
long int msg_to_receive = 0;
char buffer[BUFSIZ];
char some_text[MAX_TEXT];
//string input;
/* First, we set up the message queue. */
msgid = msgget((key_t)1234, 0666 | IPC_CREAT);
if (msgid == -1) {
fprintf(stderr, "msgget failed with error: %d\n", errno);
exit(EXIT_FAILURE);
}
/* Then the messages are retrieved from the queue, until an end message is encountered.
Lastly, the message queue is deleted. */
while(running) {
if (msgrcv(msgid, (void *)&some_data, BUFSIZ,
msg_to_receive, 0) == -1) {
fprintf(stderr, "msgrcv failed with error: %d\n", errno);
exit(EXIT_FAILURE);
}
printf("You wrote: %s", some_data.some_text);
if (strncmp(some_data.some_text, "end", 3) == 0) {
running = 1;
}
}
// msgctl performs control operations on system V message queue with identifier msqid
/*if (msgctl(msgid, IPC_RMID, 0) == -1) {
fprintf(stderr, "msgctl(IPC_RMID) failed\n");
exit(EXIT_FAILURE);
}*/
// Need to reset value, before entering second loop
// At this point enters loop, prompts user enter text
while(running) {
printf("Enter some text: ");
for (int i = 1; i < running; i++){
fgets(buffer, BUFSIZ, stdin);
some_data.my_msg_type = 1;
strcpy(some_data.some_text, buffer);
}
if (msgsnd(msgid, (void *)&some_data, MAX_TEXT, 0) == -1) {
fprintf(stderr, "msgsnd failed\n");
exit(EXIT_FAILURE);
}
if (strncmp(buffer, "end", 3) == 0) {
running = 0;
}
}
exit(EXIT_SUCCESS);
}
第一個循環在while(running)計算爲「true」時運行,但我從來沒有看到從循環中'running'設置爲'0'或'break'。 –
C++有一個布爾類型。 'running'看起來像一個布爾變量,但是你已經將它聲明爲一個整數。爲什麼? – Steve
不要緊,這一切看起來像在'.cpp'文件中的C代碼... – Steve