C variable quiz

Which of the following are valid Python code? (Select all that apply)

• echo("Hello World!")
  

• print("Hello World!")
  

• printf("Hello World!")
  

• println("Hello World!")
  

In C, what is a "variable"?

• A keyword that cannot be used as an identifier, like if or while.

• A named storage location in memory used to hold a value that can be modified.

• A block of code that performs a specific task, also known as a function.

• A fixed value that does not change during program execution, like 101.

• integer student_count;

• student_count int;

• int student_count;

• declare int student_count;

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Which of the following is a valid C variable name?

• 2_items

• total-count

• _user_level

• float

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What is the primary purpose of the const keyword when declaring a variable?

• It makes the variable accessible from any file in the project.

• It tells the compiler to store the variable in a CPU register.

• It makes the variable's value read-only and prevents it from being changed after initialization.

• It increases the memory size allocated for the variable.

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Which option correctly declares a character variable grade and initializes it to 'A'?

• char grade = "A";

• char grade = 'A';

• char grade('A');

• grade = 'A';

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A variable declared inside a function, like main, is called a...

• Local variable.

• Global variable.

• Static variable.

• External variable.

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What does the sizeof operator in C return?

• The current value stored in a variable.

• The size of a variable or data type in bytes.

• The memory address of a variable.

• The maximum value a data type can hold.

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In C, what is the data type of the result of the expression 10 + 5.5?

• int

• double

• char

• float

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What is the main characteristic of a variable declared with the unsigned keyword (e.g., unsigned int)?

• It cannot be modified after initialization.

• Its size in memory is doubled.

• It can only hold non-negative values (zero and positive numbers).

• It is automatically initialized to zero by the compiler.

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What is the initial value of a non-static local variable if you don't explicitly initialize it?

• 0

• NULL

• An indeterminate or "garbage" value.

• The code will not compile.

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In C, are the variable names totalAmount and totalamount considered the same?

• Yes, because C is not case-sensitive.

• No, because C is case-sensitive.

• Yes, but only if they have the same data type.

• It depends on the compiler settings.

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What is the defining characteristic of a local variable declared with the static keyword inside a function?

• It becomes accessible from other source files.

• It is initialized only once and retains its value between function calls.

• Its memory address cannot be taken.

• It must be a pointer type.

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What is the primary use of the extern keyword with a variable declaration?

• To create a constant variable.

• To suggest the variable be stored in a CPU register.

• To declare a variable that is defined in another source file, allowing you to use it in the current file.

• To allocate memory for the variable on the heap.

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In the C assignment statement x = 100;, the variable x represents...

• An L-value (locator value).

• An R-value (read value).

• A pointer type.

• A function call.

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What is the key difference between a variable declaration and a variable definition?

• There is no difference; the terms are interchangeable.

• A declaration specifies the type, while a definition specifies the value.

• A definition allocates storage for the variable, while a declaration only specifies its name and type without allocating storage.

• A declaration is used for global variables, and a definition is used for local variables.

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Consider this code:

int count = 10; // Global variable

void my_func() {
    int count = 5; // Local variable
    printf("%d", count);
}

What will be printed when my_func() is called?

• 10

• 5

• The code will cause a compilation error.

• It will print a garbage value.

An unsigned char can hold values from 0 to 255. What is the value of x after this code runs? unsigned char x = 255; x++;

• 256

• The program will crash with an error.

• 0

• 255

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What is the primary advantage of using double over float?

• double uses less memory.

• double is used for whole numbers only.

• double offers greater precision and a larger range of values.

• double variables are always positive.

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How do you correctly declare a variable p_age that is a pointer to an integer?

• int &p_age;

• pointer int p_age;

• int p_age;

• int *p_age;

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The volatile keyword tells the compiler that a variable's value...

• is constant and cannot be changed.

• might be changed by something outside the normal program execution flow (e.g., hardware).

• should be stored in a file instead of memory.

• is a memory address.

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What is the fundamental difference between 'A' and "A" in C?

• They are identical and can be used interchangeably.

• 'A' is a single character literal (char), while "A" is a string literal (an array of characters ending with a null terminator \0).

• 'A' is a variable, while "A" is a constant.

• "A" uses less memory than 'A'.

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Which of the following is an invalid C variable name?

• annual_salary

• __init

• final-score

• Level3

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What is the result of the statement int a, b; a = b = 20;?

• Only b is assigned the value 20; a contains a garbage value.

• Both a and b are assigned the value 20.

• Only a is assigned the value 20.

• This is a syntax error in C.

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In C99 and later, what is the standard way to declare a boolean variable is_complete?

• boolean is_complete;

• int is_complete;

• #include <stdbool.h> followed by bool is_complete;

• bit is_complete;

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What is the register storage class specifier intended to do?

• Make a variable global across all files.

• Suggest to the compiler that the variable should be stored in a fast CPU register.

• Allocate the variable's memory on the heap.

• Prevent the variable's value from being modified.

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What is the primary purpose of the char data type in C?

• To store a sequence of characters (a string).

• To store large integer values.

• To store a single character (like 'c') or a very small integer (typically -128 to 127).

• To store a number with a decimal point.

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Which statement correctly declares a floating-point variable price and initializes it to 19.99?

• float price = "19.99";

• integer price = 19.99;

• float price = 19.99f;

• price float = 19.99;

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Error processing MCQ: not enough values to unpack (expected 3, got 2)

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.14.5/x64/lib/python3.14/site-packages/mkdocs_mcq/plugin.py", line 21, in format_mcq
    _, frontmatter, content = source.split("---", 2)
    ^^^^^^^^^^^^^^^^^^^^^^^
ValueError: not enough values to unpack (expected 3, got 2)

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• [ ] 16
• [ ] 15.75
• [ ] The code will fail to compile.
• [x] 15

  Correct! Explicitly casting a double to an int truncates the value, discarding the fractional part. It does not round.

---

```mcq
---
type: single
question: A variable declared outside of all functions at the top of a source file is known as a...
----
- [x] Global variable.
  > Correct! It has file scope and is accessible to all functions within that file.
- [ ] Local variable.
- [ ] Private variable.
- [ ] Universal variable.

---

Error processing MCQ: not enough values to unpack (expected 3, got 2)

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.14.5/x64/lib/python3.14/site-packages/mkdocs_mcq/plugin.py", line 21, in format_mcq
    _, frontmatter, content = source.split("---", 2)
    ^^^^^^^^^^^^^^^^^^^^^^^
ValueError: not enough values to unpack (expected 3, got 2)

File_B.c:

extern int global_counter;

Which statements are true? (Select all that apply)

• [x] File_A.c contains a definition of global_counter.

  Correct. Memory is allocated and an initial value is provided, so this is a definition.

• [x] File_B.c contains a declaration of global_counter.

  Correct. The extern keyword tells the compiler that global_counter exists and is defined elsewhere. No memory is allocated here.

• [ ] File_B.c also defines the variable global_counter.

  Incorrect. The extern keyword explicitly makes this a declaration, not a definition.

• [ ] This code will cause a linker error because the variable is declared twice.

  Incorrect. This is the standard, correct way to share a global variable across files. A linker error would occur if both files contained a definition.

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