Chapter 10: Problem 19

What happens when a program uses the new operator to allocate a block of memory, but the amount of requested memory isn't available? How do programs written with older compilers handle this?

Short Answer

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Answer: When there is not enough memory available for allocation using the "new" operator, it throws a `bad_alloc` exception. To avoid program crashes, this exception should be handled using a try-catch block. In the case of older compilers, such as those using C, the `malloc()` function is used instead of the "new" operator. `malloc()` returns a NULL pointer when memory allocation fails. Handling memory allocation failure in older compilers involves checking the return value of `malloc()` and acting accordingly.

Step by step solution

When a program uses the "new" operator, it requests a block of memory of a specific size from the system's memory manager. If the allocation is successful, the memory manager returns a pointer to the memory location. #Step 2: Effect of unavailable memory while using the new operator#

If the requested memory is not available, the memory manager fails to allocate the block of memory. In C++, the new operator throws a `bad_alloc` exception in this circumstance. This is an exception of the `std::bad_alloc` type, which is part of the C++ Standard Library. #Step 3: Handling bad_alloc exception#

In order to avoid program crashes, this exception should be handled using a try-catch block. Here's an example: ```cpp #include #include int main() { try { int* myArray = new int[100000000]; // Request a large memory block } catch (std::bad_alloc& e) { true std::cerr

In the case of older compilers, such as those using C instead of C++, the new operator is not used. Instead, programs use the `malloc()` function to allocate memory. `malloc()` returns a NULL pointer when memory allocation fails. Checking the return value of `malloc()` is essential to handle memory allocation failure. Here's an example: ```c #include #include int main() { int* myArray = (int*) malloc(sizeof(int) * 100000000); // Request a large memory block if (myArray == NULL) { fprintf(stderr, "Unable to allocate memory.\n"); return 1; // Return an error code } // ... free(myArray); // Always free the memory when it's no longer needed return 0; // Normal exit } ``` By following these steps, students can understand the failure of memory allocation using the "new" operator when memory is insufficient and learn how older compilers handle these situations differently.

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What happens when a program uses the new operator to allocate a block of memory, but the amount of requested memory isn't available? How do programs written with older compilers handle this?

Short Answer

Step by step solution

When a program uses the "new" operator, it requests a block of memory of a specific size from the system's memory manager. If the allocation is successful, the memory manager returns a pointer to the memory location. #Step 2: Effect of unavailable memory while using the new operator#

In order to avoid program crashes, this exception should be handled using a try-catch block. Here's an example: ```cpp #include #include int main() { try { int* myArray = new int[100000000]; // Request a large memory block } catch (std::bad_alloc& e) { true std::cerr

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