C Programming Chapter 2 - Pointers
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C Programming Chapter 2 - Pointers

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Questions and Answers

What does the strlen function return?

  • The total size of the memory allocated for the string including the null character.
  • The number of characters in the string including the null character.
  • The number of characters in the string excluding the null character. (correct)
  • The number of bytes allocated for the entire string including the null character.

    • What happens if the new operator fails to allocate memory?

  • It returns a NULL pointer. (correct)
  • It returns an integer indicating the type of error.
  • It returns a pointer to the allocated memory.
  • It throws an exception.

    • Which task does the strcpy function perform?

  • Copies only the non-null characters from the source string.
  • Copies characters up to the last non-null character.
  • Copies the source string to the destination, including the null character. (correct)
  • Copies the source string to the destination, excluding the null character.

    • In pointer arithmetic, adding an integer to a pointer does what?

    <p>Increases the pointer based on the size of the data type it points to.</p> Signup and view all the answers

    Why is it important to manage dynamic memory allocation carefully?

    <p>To avoid memory leaks and exhaustion of memory resources.</p> Signup and view all the answers

    What is the expected outcome after using the strlen function on an empty string?

    <p>0, since there are no characters before the null character.</p> Signup and view all the answers

    If a programmer tries to copy more characters than allocated in the destination string with strcpy, what is likely to happen?

    <p>It will overwrite memory beyond the allocated space, potentially causing a crash.</p> Signup and view all the answers

    If an int is represented by 4 bytes, what does adding 1 to an int pointer do?

    <p>Moves the pointer to the next int value, increasing the address by 4 bytes.</p> Signup and view all the answers

    What is the correct way to dynamically allocate an array of characters to hold a string of length n using C++?

    <p>char* arr = new char[n];</p> Signup and view all the answers

    What is pointer arithmetic often used for in programming?

    <p>To iterate through arrays or other data structures.</p> Signup and view all the answers

    Study Notes

    Pointers

    • A pointer is an address of a memory location, allowing indirect access to data.
    • Pointer variables need to be defined for specific data types, e.g., int *ptr1; for integers and char *ptr2; for characters.
    • The value of a pointer variable is the address of the variable it points to, such as ptr1 = &num;, where num is an integer variable.
    • The address operator & retrieves the memory address of a variable, while the dereference operator * accesses the contents at that address, e.g., *ptr1 retrieves the value of num.
    • Pointer types must match the type of the data they point to, except for void*, which can point to any data type.
    • Pointers can be cast to different types, such as converting an int* to a char* via (char*) ptr1.

    Null Pointers

    • The null pointer (value 0) is used for initializing pointers and marking the end of pointer-based structures like linked lists.

    Dynamic Memory

    • The heap is used for dynamically allocating memory during program execution, in contrast to the program stack which is static.
    • The new operator allocates memory on the heap for a specified type and returns a pointer to it, e.g., int *ptr = new int;.
    • Memory allocated on the heap persists beyond the scope of the function that created it and must be manually released using the delete operator.
    • Functions like strlen and strcpy handle string operations; strlen counts characters up to the null terminator while strcpy copies strings including the null character.
    • Dynamic memory can become exhausted if not managed properly, leading new to return 0 when it fails to allocate.

    Pointer Arithmetic

    • Pointer arithmetic allows adding or subtracting integers to/from pointers, affecting the pointer based on the size of the data type pointed to.
    • For example, adding 1 to an integer pointer shifts the pointer by the size of an integer (e.g., 4 bytes).

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    Description

    Explore the concepts of pointers in C programming with this quiz. Learn how pointers work, how to define them, and their significance in data access. Test your understanding of pointer variables and their types.

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