如何找出C ++/C中是否已填充指针数组 [英] How to find out if a pointer array has been filled in C++/C

问题描述

假设我有功能

foo(double * pa)

foo(double * pa)

其中pa从[0]填充到[100] 或者 pa仅填充为[0].

where pa is either populated from [0] to [100] OR pa is populated for [0] only.

我的功能执行以下操作:

My function does the following:

foo(double * pa)

foo(double * pa)

{

IF(pa是100的数组)则x [0到100] = pa [0到100]

IF (pa is an array of 100) THEN x[0 to 100] = pa[0 to 100]

ELSE x [0至100] = pa [0]

ELSE x[0 to 100] = pa[0]

}

推荐答案

问:foo()如何知道pa []是否为100的数组?

Q: How is foo() going to know whether pa[] is an array of 100?

通常，您必须告诉它.例如:

In general, you have to TELL it. For example:

void
foo (double *pa, int len)
{
  if (len == 100)
    ...
  else
    ...

但是，如果您使用C ++进行编码，则可以使用STL容器，例如矢量:

If you were coding in C++, however, you could use an STL container such as a vector:

void foo (vector<double> & pa)
{
  if (pa.size() == 100)
    ...

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