Question

#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<stdlib.h>
#include<string.h>
#define MAX_LINE 80 /* Maximum  length of command*/

struct memList
{
 char commandName[41];
 char restCommandName[41];
 struct List *next;
};



void addToList(char [], char [], int);

int main()
{
 char *args[MAX_LINE/2+1]; /* Command Line Argument*/
 int should_run=1, status, i, num;
 pid_t pid;
 char str[41], teststr[41];
 const char delimiter[2]=" ";
 char *token;


 while(should_run)
{
i=0;
printf("osh>");
fflush(stdout);

fgets(str, sizeof str, stdin);
str[strlen(str)-1]='\0';
token=strtok(str, " ");

    while(token)
    {
       args[i]=strdup(token);
       printf("args[%d]=%s\n", i, args[i]);
       i++;
       token=strtok(NULL, " ");
    }
    if(args[0]=="history")
    {
        addToList(args[0], str, 1);
    }
    else
    {
        addToList(args[0], str, 0);
    }
    pid=fork();
    if(pid<0)   // error in creating child process
    {
       printf("\tError in creating child process\n");
    }       
    else if(pid==0)    //child process will execute this block
    {
       printf("\tChild running it's block\n");

       execvp(args[0], args);
                 exit(1);
    }
    else        //parent process will execute this block
    {
       pid=wait(&status);
       printf("\tNow Parent resumes\n");

    if(!strcmp(args[0], "exit"))
    {
            should_run=0;
    }
}
}
return 0;
} 

void addToList(char cmd[], char restCmd[], int flag)
{
 int i;
 struct memList *head=NULL;          //In this function node is created
 struct memList *ptrNode=NULL;       // and added to the list
 struct memList *temp=NULL;
 ptrNode=(struct memList *)malloc(sizeof(struct memList));
 memset(ptrNode, 0, sizeof(struct memList));
 strcpy(ptrNode->commandName, cmd);
 strcpy(ptrNode->restCommandName, restCmd);
if(head==NULL)
{
 head=ptrNode;

}
else
{
 ptrNode->next=head->next;
 head=ptrNode;
}


if(flag)      //if flag=1 i.e. if args[0]=history then the whole list will get printed
{                //this block of code shows error
 temp=head;         //assignment for incompatible pointer type
 while(temp!=NULL)
 {
  printf("%d %s", i, temp->commandName);
  temp=temp->next;
 }
}
}

如果我的代码中存在任何其他现有内存泄漏以及我将args [0]作为参数传递给函数addToList（），请告诉我。那是对的吗。如果没有，那我该怎么做呢。

Answer 1

问题是struct List *是一个与struct memList *不同的指针类型，所以temp = temp-＆gt; next;给出编译器错误。（在gcc-4.7.2中，错误信息是：在分配时无法将'List *'转换为'memList *'）

按如下方式更改struct memlist声明：

struct memList
{
    char commandName[41];
    char restCommandName[41];
    struct memList *next; // instead of struct List *next;
};

从不兼容的指针类型c分配

1 个答案: