Topic: (C++)How to get object from vector one by one in a loop? thanks. After I erase an element from a list,where the pointer will point to? @枫下论坛 The Rolia Forum

工作学习 / IT技术讨论 / (C++)How to get object from vector one by one in a loop? thanks. After I erase an element from a list,where the pointer will point to? -wendywendy(wind); 2001-7-22 (#140905@0)

再详细点，第二个问题pointer是指哪一个？ -rock_jack(The Door); 2001-7-22 (#140951@0)
template -jfhuang(Zigzag); 2001-7-22 {324} (#141106@0)
use iterator:
vector<object>::iterator aIterator;

for (aIterator = aVector.begin();aIterator != aVector.end();aIterator++){
// loop
}

the statement to remove an element from a vector is:
aIterator2 = aVector.erase(aIterator1);
aIterator2 is an iterator which desigates the next available element.

in my interview, a question is :what's wrong -wendywendy(wind); 2001-7-23 {238} (#141715@0)
for (aIterator = aVector.begin();aIterator != aVector.end())
{
if (aVector.get(aIterator )==0)
aIterator =aVector.erase(aIterator );
alterator++;

}

so, if the last element is 0,error ?I failed to answer this question

if alterator points to the last element, aVector.erase(aIterator ) will return end(). -jfhuang(Zigzag); 2001-7-23 {312} (#142228@0)
So you have to check if alterator is at the end. Otherwise you will get an error. The modified code is as follows,

for (aIterator = aVector.begin();aIterator != aVector.end())
{
if (aVector.get(aIterator )==0)
aIterator =aVector.erase(aIterator );
if (aIterator != aVector.end()) alterator++;

}

It seems that you are an expert in C++, could you please help me? Just some simple questions.Thank you! -lynx(jane); 2001-7-23 {1584} (#142238@0)
本文发表在 rolia.net 枫下论坛I installed VC++6.0 this morning and tried the program. But it still had some problems:
1, I want to know a function that can read the current time of the system, and how to use it. Is it read the seconds or the minutes?In C, it is called biostime().
2, I built the .exe file and I ran it. The program first just read some parameters as you input them, and also the .dat file name. Please see below:

1 printf(" Please input learning factor---Et & dEt: (
Note:0.1>=Et>=0) \n");
2 scanf("%f",&Et);
3 scanf("%f",&dEt);

4 printf(" Please slope value of g() --- alfa:\n");
5 scanf("%f",&alfa);
6 printf(" Please input learning factor---beita:\n");
7 scanf("%f",&beita);
8 printf(" Please input learning factor---bstep:\n");
9 printf(" ( Note: 0.1beita>bstep>0.000 ) \n");
10 scanf("%f",&bstep);

11 gets(ldfnm);
12 printf(" Please input learning data file name(iol?.dat):\n");
13 gets(ldfnm);

14 sss=fopen(ldfnm,"r");
15 fscanf(sss,"%d%d",&inputN1,&inputN1);
16 fscanf(sss,"%d",&modelN);
17 outputN=62;
18 position=ftell(sss);
19 p=position;
20 fclose(sss);

So the above part works until line 13, I can input all those parameters. But when I input the .dat file name (line 12 stll works), it stop working. A window jump out and said that
"Debug assertion failure.
Program: D:\program\Debug\learning.exe
File: fscanf.c
Line: 54
expression: streams!=NULL"

Could you please tell what's wrong with the program? What means assertion failure?How to deal with it?
Thank you very much!更多精彩文章及讨论，请光临枫下论坛 rolia.net

Several ways can be used to get the current time -jfhuang(Zigzag); 2001-7-24 {679} (#143677@0)
1. You can try GetSystemTime() as follows:

SYSTEMTIME currentTime;
int second, minute;
GetSystemTime(&currentTime);

second = currentTime.wSecond;
minute = currentTime.wMinute;
.......

2. I don't know how you define the string ldfnm. You should define char ldfnm[30], or something like that, to allocate memory. Otherwise you may get an error.
Assertion is a debug method. The statement is like : assert(x==1). if x does not equal to 1, the program will raise an assertion failure. It can help you to debug the program. There are a lot of assertion statement in the C/C++ library to help you debug your programm.

Thank you very much and I have sloved the problems. -lynx(jane); 2001-7-24 (#143694@0)

There are several ways to get the current time -jfhuang(Zigzag); 2001-7-24 {679} (#143680@0)
1. You can try GetSystemTime() as follows:

SYSTEMTIME currentTime;
int second, minute;
GetSystemTime(&currentTime);

second = currentTime.wSecond;
minute = currentTime.wMinute;
.......

2. I don't know how you define the string ldfnm. You should define char ldfnm[30], or something like that, to allocate memory. Otherwise you may get an error.
Assertion is a debug method. The statement is like : assert(x==1). if x does not equal to 1, the program will raise an assertion failure. It can help you to debug the program. There are a lot of assertion statement in the C/C++ library to help you debug your programm.

good,good, thanks,thanks. -qiuqiu(秋秋); 2001-7-23 (#142240@0)
thanks. u r so helpful -wendywendy(wind); 2001-7-25 (#143834@0)