Question

这是一个关于管道和进程的小C程序，父进程将创建2个子进程，第一个将读取链中的数字，第二个将读取字母。我开始要求WORD，我没有添加保护，这只是一个测试，所以让我们说大约20个字母，然后父进程将在第一个管道中写入数字，并在第二个管道中写入字母，然后他将创建一个孩子使用fork（），如果他是孩子，他将从第一个管道读取数字，如果他是父亲，那么他将创建另一个孩子，阅读这些字母。

# include <stdio.h>
# include <unistd.h>
# include <string.h>
# include <fcntl.h>

main()
{
    printf("I am the father, I will create 2 sons, the first will read the numbers , the second will read the letters\n");
    char * word;
    printf("please type the word: \n");
    scanf("%s",word);
    printf("Now 2 pipes will be created\n");
    int fd1[2];
    int fd2[2];
    pipe(fd1); pipe(fd2);
    printf("Now the father will write numbers in the first pipe, and letters in the second\n");
    int i;
    char numbers[20]; int j=0;
    char caracters[20]; int k=0;
    for (i=0;i<20;i++)
    {
        if(word[i]>='0' && word[i]<='9') //if number
        {
            close(fd1[0]); //closing reading
            write(fd1[1],word[i],2);

        }
        else
        {
            close(fd2[0]);  
            write(fd2[1],word[i],2);
        }

    }
    printf("The father has wrote in the 2 pipes, now its time for the sons\n");
    int f=fork();
    if(f==0) //first son
    {
        for(i=0;i<20;i++) {         
            close(fd1[1]); //closing writing
            read(fd1[0],numbers[j],strlen(numbers[j])+1);
            j++;

        }
        printf("first son read everything, he got %d Numbers\n", j);
    }
    else
    {
        f=fork();
        if(f==0)
        {
            for(i=0;i<20;i++) {         
            close(fd2[1]); //closing writing
            read(fd2[0],caracters[k],strlen(caracters[k])+1);
            k++;

        }   
        printf("second son read everything, he got %d caracters\n", j);
    }
}

编译后

：

In function 'main':
Line 25: warning: passing argument 2 of 'write' makes pointer from integer without a cast
Line 31: warning: passing argument 2 of 'write' makes pointer from integer without a cast
Line 41: warning: passing argument 1 of 'strlen' makes pointer from integer without a cast
Line 41: warning: passing argument 2 of 'read' makes pointer from integer without a cast
Line 54: warning: passing argument 1 of 'strlen' makes pointer from integer without a cast
Line 54: warning: passing argument 2 of 'read' makes pointer from integer without a cast
Line 60: error: expected declaration or statement at end of input

Answer 1

write和read的原型是

ssize_t write(int fd, const void *buf, size_t count);

ssize_t read(int fd, void *buf, size_t count);

write / read的参数2应该是一个指针。但是你发送的是一个字符（实际上是一个整数）word[i]和numbers[i]

即使您的strlen

也存在同样的问题

此外，将word声明为数组而不仅仅是指针。否则，您将写入指针所指向的随机位置。或者如果你想把它作为一个指针，malloc为它留下一些记忆。

完成所有这些操作后，只需将word，numbers代替numbers[j]或words[i]传递给投诉的函数

编辑：您的上一个for语句for(i=0;i<20;i++)也没有右括号，因此Line 60: error: expected declaration or statement at end of input错误

Answer 2

而不是：

write(fd1[1],word[i],2);

这样做：

write(fd1[1],(void*)&word[i],2);

...即，将一个POINTER传递给数据的位置，而不是数据本身的值。

WRITE和READ有什么错误？

2 个答案: