定义YYSTYPE结构节点1 *
%token INT FLOAT CHAR DOUBLE VOID
开始:声明函数声明1 {$$ = mknode($1, $2, $3,NULL,0);}
|Declaration Function {$$=mknode($1,$2,NULL,NULL,0);}
| Declaration {$$ =mknode($1,NULL,NULL,NULL,0); }
| Function {$$ =mknode($1,NULL,NULL,NULL,0); }
;
Declaration1 :Function {$$ =mknode($1,NULL,NULL,NULL,NULL); }
;
Function:
Type ID '(' ArgListOpt ')' CompoundStmt {$$ = mknode($1,$2,$4,$6,NULL); }
;
类型:INT {$$ = mknode(NULL,NULL,NULL,NULL,"INT"); }
| FLOAT {$$ = mknode(NULL,NULL,NULL,NULL,"FLOAT"); }
| CHAR {$$ = mknode(NULL,NULL,NULL,NULL,"CHAR"); }
|双 {$$ = mknode(NULL,NULL,NULL,NULL,"DOUBLE"); }
| VOID {$$ = mknode(NULL,NULL,NULL,NULL,"VOID"); }
;
CompoundStmt: '{' StmtList '}' {$$ =$2; }
;
StmtList: StmtList Stmt {$$ = mknode($1,$2,NULL,NULL,NULL); }
| {$$=mknode(NULL,NULL,NULL,NULL,NULL);}
;
when i am running this on the input
int mian()
{}
it is giving segementation fault at
char* newnode =(char*)malloc(strlen(token));
node1 *mknode(node1 *left1, node1 *left2, node1* left3,node1* left4,char *token)
{
/* malloc the node */
node1 *newnode = (node1 *)malloc(sizeof(node1));
char *newstr = (char *)malloc(strlen(token));
strcpy(newstr, token);
newnode->left1 = left1;
newnode->left2 = left2;
newnode->left3 = left3;
newnode->left4 = left4;
newnode->token = newstr;
return(newnode);
}
这里有什么错误吗?请帮忙
最佳答案
虽然您确实应该在调试器中运行程序来找出答案,但这两行可能是罪魁祸首:
char *newstr = (char *)malloc(strlen(token));
strcpy(newstr, token);
如果token
为NULL
,那么strlen
和strcpy
很可能会崩溃。
取消引用 NULL
指针是未定义的行为,并且在大多数情况下会导致崩溃。在取消引用指针或调用执行此操作的函数之前,您需要检查指针是否为 NULL。
关于c - 段错误(核心转储)调用 mknode 函数时出错,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18204401/