A ________ occurs when a program continues to use a pointer after it has been freed.
- Buffer Overflow
- Dangling Pointer
- Memory Leak
- Segmentation Fault
A Dangling Pointer occurs when a program continues to use a pointer after it has been freed. This can lead to undefined behavior, crashes, or data corruption. It's crucial to avoid using pointers that point to memory that has been deallocated.
Why would you use a pointer to an array instead of a regular array in a function?
- Pointers allow you to modify the original array in a function.
- Pointers allow you to pass arrays to functions without making a copy.
- Pointers are more memory-efficient than regular arrays.
- Pointers provide a way to dynamically allocate memory for arrays.
Using a pointer to an array in a function allows you to pass the array by reference, avoiding the need to make a copy of the array. This is more memory-efficient and allows you to modify the original array within the function.
When working with binary files, the ________ function can be used to read data in a structured manner.
- fread()
- fgets()
- fgetc()
- fscanf()
The correct option is fread(). This function is specifically designed for reading binary data from a file. It takes parameters like the file pointer, size of each element, number of elements, and the destination buffer where the data will be stored. This makes it suitable for structured reading of binary files.
The ______ stream in C is used for unbuffered error messages.
- stderr
- stdout
- printf
- ferror
The correct option is a) stderr. The stderr stream is used for unbuffered error messages in C programs.
When defining a structure in C, memory is not allocated until an ________ of the structure is created.
- array
- function
- instance
- pointer
In C, memory for a structure is not allocated until an instance of the structure is created. An instance represents a specific object based on the structure's definition.
You're working on an embedded system with limited memory. What feature of C would you use to efficiently pack multiple flags into a single byte?
- Bit fields
- Pointers
- Inline functions
- Function pointers
Option A, "Bit fields," is the correct choice. Bit fields allow you to efficiently pack multiple boolean flags into a single byte, which is essential in resource-constrained embedded systems, helping to save memory. Bit fields provide control over the size and alignment of data within a structure, allowing you to use memory more efficiently. Other options are not typically used for this purpose and may not offer the same level of memory optimization. Bit fields are an important concept for embedded systems programming.
In a large C program, you notice that a variable is being used in multiple functions but is not behaving as expected. What could be the potential issue regarding the scope of the variable?
- The variable is a global variable
- The variable is a local variable
- The variable is a static variable
- The variable is an automatic variable
The potential issue with the variable not behaving as expected could be that it is a global variable. Global variables have a larger scope and can be modified by multiple functions, which may lead to unintended changes. It's important to be cautious when using global variables in large programs. Static variables retain their values but have a limited scope, making them less likely to cause scope-related issues. Automatic and local variables are confined to individual functions and are less likely to impact other parts of the program.
The fseek function allows for ________ access of data within a file.
- random
- direct
- sequential
- indexed
The correct option is sequential. The fseek() function, when used with SEEK_SET, SEEK_CUR, or SEEK_END, allows for sequential access to data within a file. It enables you to move the file pointer forward or backward, or directly to the end of the file, facilitating sequential data access.
How can you handle an error when attempting to allocate memory using malloc() in a C program?
- Check if the return value of malloc() is NULL and handle accordingly.
- Use try-catch blocks to handle memory allocation errors.
- Set a flag in case of an error and handle it in a separate error-handling function.
- Call exit() to terminate the program if malloc() fails.
The correct option is "Check if the return value of malloc() is NULL and handle accordingly." Malloc() returns a NULL pointer if it fails to allocate memory. It's crucial to check this return value to handle memory allocation errors gracefully.
How is the size of a union determined in C?
- By the number of members
- By the size of its largest member
- By the size of its smallest member
- By the sum of the sizes of its members
In C, the size of a union is determined by the size of its largest member. If you have a union with multiple members, the size will be at least as large as the largest member's size.