The ________ directive allows for conditional compilation in a C program.
- #ifdef
- #ifndef
- #include
- #pragma
In C programming, the #ifdef directive is used for conditional compilation. It checks if a particular macro is defined and includes code if the macro is defined.
How can you position the file pointer to the end of a file using fseek?
- fseek(file, SEEK_END)
- fseek(file, FILE_END)
- setpos(file, END)
- setfilepos(file, SEEK_END)
The correct option is fseek(file, SEEK_END). This command uses the fseek function to move the file pointer to the end of the file, facilitating operations like appending data to the end of a file in C.
What function is commonly used in C for taking user input?
- gets
- printf
- puts
- scanf
The 'scanf' function is commonly used in C for taking user input. It allows you to read input values from the user and store them in variables.
When using typedef to create a function pointer alias, what aspect of the function signature must be included in the alias?
- Function name
- Return type
- Parameter types
- Number of parameters
The correct option is b) Return type. When using typedef to create a function pointer alias, you must include the return type of the function in the alias. This ensures that the alias correctly represents the function pointer's signature, allowing you to use it to declare and call functions.
When reading a file in C, which function can be used to check if the end of the file has been reached?
- endOfFile()
- feof()
- fileEOF()
- file_end()
The correct function is feof(), which stands for "file end of file." It returns a non-zero value if the end of the file has been reached, indicating that there are no more characters to read.
In which scenarios would it be beneficial to use double pointers in C?
- Dynamic memory allocation
- Linked lists
- Matrix operations
- String manipulations
Double pointers are often used in scenarios like linked lists, where you need to manage a list of pointers. They also come in handy when dealing with matrices and strings, as they allow you to have multiple levels of indirection for better control and memory management.
What function is commonly used to find the length of a string in C?
- strcat()
- strcmp()
- strcpy()
- strlen()
In C, strlen() is commonly used to find the length of a string. It counts the number of characters in a string until the null-terminator is encountered.
When you define a union, the compiler allocates memory based on the ________ member of the union.
- first
- largest
- last
- smallest
The compiler allocates memory based on the largest member of the union to ensure that it can accommodate the largest data type within the union, which is known as the "largest member rule."
You're working on a C program that must adapt to different operating systems. How can preprocessor directives be used to ensure that the right code is compiled for the right operating system?
- By using the 'if-else' statement
- By using 'while' loops
- By using 'ifdef' and 'ifndef'
- By using 'for' loops
Preprocessor directives, such as 'ifdef' and 'ifndef,' can be used to conditionally compile code based on the target operating system. This ensures that the correct code is included for each OS. Options a, b, and d do not relate to OS-specific compilation.
What does the 'NULL' pointer represent in C?
- A pointer to a constant value
- A pointer to a non-existent location
- A pointer to the keyboard input
- A pointer to the main function
The 'NULL' pointer in C represents a pointer that doesn't point to any memory location. It's often used to indicate that a pointer is not currently pointing to valid data.