flyonok

统计

留言簿(8)

ACE

book

boost

bsd

c study

c++

code download

codeblock

computer clound

Eclipse

embed system

erlang

ET++

gtk

ic card

java

KDE

libevent

linux

linux--MM

mysql

network education

one card

oracle

pcap relation

php

powerbuilder

python

QT

software config

software test

SQL server

UML

wireless

wxwidgets

陈宾

阅读排行榜

评论排行榜

c++ memory test

Question #1 When will this line fail to compile: new myObj[100];
a) Never
b) When myObj is too large to fit into memory
c) When myObj has no default constructor

Question #2 Assuming that myObj is less than 1000 bytes, is there anything wrong with this code?
char x[1000];
 myObj *obj = reinterpret_cast(x);
new (obj) myObj;
 a) Nope, it works fine
b) Yes, there could be byte alignment issues
c) Yes, the syntax for calling new is incorrect

Question #3 What is the functional difference between
myObj *x = new myObj[100]; delete x; and myObj *x = new myObj[100]; delete [] x;
 a) There is none; they both work as expected
b) They both do nothing.
c) The first will not invoke all myObj destructors

Question #4 What is wrong with the following code? int * x = (int *) malloc(100 * sizeof(int)); x = realloc(x, sizeof(int) * 200);
a) If realloc fails, then the original memory is lost
b) Nothing, realloc is guaranteed to succeed (by returning the original pointer)
c) Nothing, realloc frees the original memory passed to it 

Question#5 What is one possible symptom of having called free on the same block of memory twice?
a) Nothing, calling free twice on one block of memory always works fine
b) Malloc might always return the same block of memory
c) You cannot free any memory in the future 

Question#6 What's wrong with this line of code? int *x = NULL; delete x;
a) It causes a segmentation fault when delete tries to access NULL
b) Nothing
c) It is undefined behavior

Question #7 Assuming this code were being compiled using a standards-conforming C++, what is wrong with it? int * x = malloc(100 * sizeof(int)); x = realloc(x, sizeof(int) * 200);
a) malloc is undefined in C++, you can only allocate memory using new
b) Invalid cast from a void* to an int*
c) Nothing is wrong with this code

Question #8 What is the default behavior of the normal new operator failing?
 a) This is left up to the implementation to decide
b) It returns NULL
c) It throws an exception

Question #9 What is a difficulty that arises with handling out of memory errors?
a) Many cleanup operations require extra memory
b) Running out of memory rarely happens in systems that interact with users
c) Once you've run out of memory, your program cannot continue

 Question #10 What is the result of this code? myObj *foo = operator new(sizeof(foo));
a) That's not legal syntax!
b) foo has memory allocated for it, but is not constructed
c) foo has memory allocated for it, and is fully constructed

posted on 2010-05-18 11:54 flyonok 阅读(618) 评论(0)  编辑 收藏 引用 所属分类: c++


只有注册用户登录后才能发表评论。
网站导航:   博客园   博客园最新博文   博问   管理