Handle memory allocation failure errors

1. Functions of malloc/calloc/realloc/valloc/alloca/memalign in C:

Such a memory allocation function returns a null pointer when the memory allocation fails.,Therefore,When a call returns,The method for checking the return value is relatively simple.,You only need to compare it with a null pointer.;

For example:

Char * P = (char *) malloc (1204);

If (P = NULL)

{

// Error handle;

};

Char * PP = (char *) calloc (3,1024);

If (Pp = NULL)

{

// Error handle;

};

Ii. New operator in C ++:

When the new operator in C ++ fails to allocate memory, the default operation throws a built-in exception. , Instead of directly returning a null pointer ; In this case , Then compare the returned value with a null pointer. , It makes no sense. ; Because , After C ++ throws an exception , Just jump out of the line where the new operator is located.Code , Instead of executing subsequent code lines , So , The code for determining the return value of the new operator cannot be executed. ; Of course , The standard C ++ also provides methods to suppress exceptions thrown. , So that the exception of memory allocation failure is no longer ruled out , Returns a null pointer directly. , This is because there may be no exception handling mechanism in the old compiler. , Exceptions cannot be caught. ; For example:

Int * P = new int [size];

If (P = 0) // check if p is a null pointer;This judgment is meaningless.;

{

Return-1;

}

So,There are two methods in C ++ to handle the memory allocation failure error of the new operator.;

1. Capture the exception thrown by the new operator:

Char * P = NULL;

Try

{

P = new char [1024];

}

Catch (const STD: bad_alloc & Ex)

{

// Exception handle;

Return-1;

}

2. Suppress the exception throw:

char * P = NULL ;

P = new (STD: nothrow) Char [1024] ; // , if new memory allocation fails , No exception is thrown. , instead, a null pointer is returned. ;

If (P = NULL) // This judgment makes sense.;

{

// Error handle;

Return-1;

}

Original article:

Http://blog.csdn.net/app_12062011/article/details/7302673