C菜单语法错误 [英] C menu syntax error

问题描述

您好我的c菜单脚本上有语法错误，我无法弄清楚如何解决



错误：

./ menu.c：第2行：意外令牌附近的语法错误`（'

'/ menuu.c：第2行：`void菜单（无效）;



代码：

Hi i have a syntax error on my c menu script that i cant figure out how to resolve

Error:
./menu.c: line 2: syntax error near unexpected token `('
'/menu.c: line 2: `void Menu(void);

Code:

#include <stdio.h>
void Menu(void);
void Top(void);
void Watch(void);
void ping(void);
void Muilt_ping(void);
 
int main(int argc, char** argv)
{
    Menu();
    return 0;
}
 
void Menu(void)
{
    int choice;
 
    do
    {
        printf("-------------------Menu--------------------\n");
        printf("|          1. Run Top as child            |\n");
        printf("|          2. Run Watch as child          |\n");
		printf("|          3. Ping Google as child        |\n");
		printf("|    4. Ping both the Google and Bing     |\n");
        printf("|                as child                 |\n");
        printf("|          5. Exit                        |\n");
        printf("-------------------------------------------\n\n");
        scanf("%d",&choice);
 
        switch(choice)
        {
            case 1: Top();
                break;
            case 2: Watch();
                break;
			case 3: ping();
				break;
			case 4: Muilt_ping();
				break;
            case 5: printf("Exiting program!\n");
                exit(0);
                break;
            default: printf("Invalid choice!\n");
                break;
        }
 
    } while (choice != 5);
 
}
 
void Top(void)
{
        int ch;
		int pid= fork() ;
        if(pid!=0) {
                wait();
                printf ( " Parent PID = %d, The PPID = %d, \n ",getpid(),getppid());
                printf( "Child process has finished. \n ");
        }else {
        printf ( " Child PID = %d , The PPID is %d \n",getpid(),getppid());
        sleep(2);
        execl ( "/usr/bin/top",".",(char*)0);
        
 
    /* Flushes input buffer from the newline from scanf() */
    while ( (ch = getchar()) != '\n' && ch != EOF) ;
 
    printf("\n\nPress ENTER to continue.");
    while ( (ch = getchar()) != '\n' && ch != EOF)
        ;
 
    return;
}  
}     

void Watch(void)
{
    int ch;
	int pid= fork() ;
        if(pid!=0) {
                wait();
                printf ( " Parent PID = %d, The PPID = %d, \n ",getpid(),getppid());
                printf( "Child process has finished. \n ");
        }else {
        printf ( " Child PID = %d , The PPID is %d \n",getpid(),getppid());
        sleep(2);
        execl ( "/usr/bin/watch",".",(char*)0);
        
 
    /* Flushes input buffer */
    while ((ch = getchar()) != '\n' && ch != EOF) ;
 
    printf("\n\nPress ENTER to continue.");
    while ((ch = getchar()) != '\n' && ch != EOF);
 
    return;
}
}

void ping(void)
{
	
    int ch;
	int pid= fork() ;
        if(pid!=0) {
                wait();
                printf ( " Parent PID = %d, The PPID = %d, \n ",getpid(),getppid());
                printf( "Child process has finished. \n ");
        }else {
        printf ( " Child PID = %d , The PPID is %d \n",getpid(),getppid());
        sleep(2);
        execl( "/bin/ping", "ping", "-c 5", "www.google.com", (char*)NULL);
		
	return;
}
}
void Muilt_ping(void)
{
		int ch;
		int pid= fork() ;
        if(pid!=0) {
                wait();
                printf ( " Parent PID = %d, The PPID = %d, \n ",getpid(),getppid());
                printf( "Child process has finished. \n ");
				if(fork()) {
					wait();
					printf ( " Parent PID = %d, The PPID = %d, \n ",getpid(),getppid());
					printf( "Child process has finished. \n ");
				}else {
				printf ( " Child PID = %d , The PPID is %d \n",getpid(),getppid());
				sleep(2);
				execl( "/bin/ping", "ping", "-c 5", "www.google.com", (char*)NULL);

		}
		}		
		
		else {
        printf ( " Parent PID = %d, The PPID = %d, \n ",getpid(),getppid());
        sleep(2);
        execl( "/bin/ping", "ping", "-c 5", "www.bing.com", (char*)NULL);
		}return;
		}

我的尝试：



某处告诉我，我可以移除空洞，但这不起作用。

菜单（）;

顶部（）;

观察（）;

ping（）;

Muilt_ping（）;

What I have tried:

Somewhere told me i could remove the voids but this didn't work.
Menu();
Top();
Watch();
ping();
Muilt_ping();

推荐答案

使用

Using

gcc -Wall -c menu.c

您的问题中显示的错误不会发生。但是还有其他一些错误和警告。其中大多数都可以通过包含额外的头文件来避免：

the error shown in your question does not occur. But there are some other errors and warnings. Most of them can be avoided by including additional header files:

# include <stdio.h>
# include <stdlib.h>
# include <unistd.h>
# include <sys/types.h>
# include <sys/wait.h>

然后只剩下一个错误。 wait（）函数需要一个参数。请参阅 wait（2） - Linux手册页 [ ^ ]。您也可以通过在shell中输入相应的 man 命令来显示该页面：

Then there is only one error left. The wait() function requires a parameter. See wait(2) - Linux man page[^]. You may also show that page by entering the corresponding man command at the shell:

man 2 wait

你可以删除空白的 一些 ：

You can remove some of the voids:

void Menu()
   {
   int choice;
   ...
void Top()
   {
   int ch;
   ...

但是您需要在声明开始时使用。

当您调用函数时，您不应尝试包含它们：

But you need the one at the start of the declaration.
And you are right not to try and include them when you call the functions:

Menu();

没问题。

但是......如果我在这里尝试你的代码，它编译得很好，没有错误。

所以检查你的编译器选项并确保你使用的是C编译器并将其传递给正确的文件！

Is fine.
But...If I try your code here, it compiles fine, with no errors.
So check your compiler options and make sure you are using a C compiler and passing it the right file!

为了编译它你必须包含正确的头文件，即： stdlib.h 和 unistd.h 。

In order to compile it you have to include the proper headers, namely: stdlib.h and unistd.h.

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