Notes on C Programming Concepts

Executable Statements

• Course: COP 3223C - Introduction to Programming with C
• Instructor: Yancy Vance Paredes, PhD.

Assignment Statements

• Assignment statements store a value or a result to a variable.
• The assignment operator is =.
• Important Note: Unlike in mathematics, the = symbol is not symmetric!

Syntax

• Syntax structure:
  variable_name = expression;
• The expression can be either a literal value or the result of a computation.
• Example:
  ```c
  int num;
  num = 10;

- **Advance example:**  

c
int num1, num2;
int result;
num1 = 10;
num2 = 20;
result = num1 + num2;

- Add additional computations to `result`:  

c
result = num1 + num2 + 50;
result = result + 10;
result = result + 10;
result = result + result;

- **Key Reading Tip:**  
  - Always read code from top to bottom.  
  - In assignment statements, evaluate the right-hand side first before assigning it to the left-hand side.  

### Your Turn!  

c

include

int main(void) {
int sum = 0;
int num;
num = 5;
sum = sum + num;
sum = sum + num;
sum = sum + num;
return 0;
}

#### Question: What is the final value of `sum`?  
- **Solution:**  
  - `sum` will equal 15 after executing the program.

### Input/Output (I/O) Operations  
- **Input Operation:**  
  - Copies data from input devices (e.g., keyboard) into memory.  
- **Output Operation:**  
  - Displays information stored in memory.  

### I/O Functions in C  
- Functions for I/O operations are defined in the `stdio.h` library.  
- Common Functions:  
  - `printf()`: Outputs formatted data.  
  - `scanf()`: Inputs formatted data.  

### The `printf()` Anatomy  
- Example of using `printf`:  

c
printf("Hello, World!\n");

- Breakdown:  
  - **Function Name:** `printf`  
  - **Format String:** A string enclosed in double quotes.  
  - **Argument Count:** The number of arguments passed.  

#### Format Specifiers  
- Placeholders:  
  - `%d`: integer  
  - `%lf`: double  
  - `%f`: float  
  - `%c`: character  
- **Example:**  

c
int num = 10;
printf("The value of num is: %d\n", num);

### Escape Sequences in C  
- Common escape sequences and their meanings:  
  - `\a`: Alert  
  - `\b`: Backspace  
  - `\n`: Newline  
  - `\t`: Horizontal Tab  
  - `\\`: Backslash  
  - `\'`: Single Quote  
  - `\"`: Double Quote  
  - `\?`: Question Mark  
  - `%%`: Percent Symbol  

### The `scanf()` Anatomy  
- Example usage:  

c
int num;
scanf("%d", &num);

- Breakdown:  
  - Uses `&` operator to specify the address where the input value is stored.  
- **Example:**  

c
int num;
printf("Enter a number: ");
scanf("%d", &num);
printf("The value of num is: %d\n", num);

### Common Mistakes with `scanf()`  
- Wrong placeholder usage:  

c
int num;
scanf("%f", &num);

- Forgetting to use the `&` operator:  

c
scanf("%d", num);

### The `return` Statement  
- Terminates the function and returns control to the calling function (or OS for `main()`).  
- **Example:**  

c
return 0;
```

• Can be used in functions where it is followed by a semicolon.

Questions?

• Any further inquiries about this content?