Questions and Answers
A pointer can be assigned the value 0, which is referred to as the null pointer.
True
The heap is used for allocating static memory during program execution.
False
The new operator is used to deallocate memory blocks in the heap.
False
Memory allocated from the heap remains valid even after the function that created it returns.
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Using the delete operator is mandatory after every new allocation to prevent memory leaks.
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Pointer arithmetic can be used directly with pointers to access elements in an array.
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When copying strings using pointers, it is not necessary to allocate memory for the new string.
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The delete operator can be used to release memory allocated for both single variables and arrays.
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A pointer must always be initialized before use to avoid pointing to unintended memory.
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Dynamic memory allocation can fail, resulting in a null pointer if the system runs out of memory.
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Study Notes
String Functions in C++
-
strlencounts characters in a string up to the null character, excluding it from the count; add 1 to allocate enough space. -
strcpycopies strings character by character, including the null character. - If dynamic memory allocation fails using
new, it returns 0; it's the programmer's responsibility to handle such scenarios.
Pointer Arithmetic
- Pointer arithmetic allows adding or subtracting integers from pointers, influencing memory addressing.
- Example:
char *str = "HELLO";andint *ptrto an integer array. - Incrementing
strmoves by one byte, while incrementingptrmoves by the size of an integer (4 bytes). - Elements can be accessed via
*str,*(str + 1), etc., for characters, and*ptr,*(ptr + 1), etc., for integers. - Subtracting pointers of the same type provides the difference in their positions within the array.
String Copying Function Example
- A simple function to copy strings might look like:
void CopyString (char *dest, char *src) { while (*dest++ = *src++) ; } - The loop assigns characters from
srctodest, incrementing both pointers until a null character is reached.
Null Pointer
- A pointer can be assigned a value of 0, referred to as the null pointer.
- Null pointers are useful for initializing pointers and marking the end of structures like linked lists.
Dynamic Memory Management
- Memory can be allocated from two areas: the stack (static memory) and the heap (dynamic memory).
- The
newoperator allocates memory on the heap, returning a pointer; e.g.,int *ptr = new int;. - Heap memory does not have the same scope rules as stack memory. For example, memory allocated within a function persists even after the function exits.
- The
deleteoperator is essential for releasing memory allocated withnewto prevent memory leaks.
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Description
This quiz covers essential string functions in C, particularly focusing on strlen and strcpy. You'll learn how to effectively use these functions for string manipulation, including character counting and copying. Test your knowledge of C's string handling capabilities!
