C Programming - Variables and I/O Lecture 2
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Questions and Answers

What is the primary purpose of the printf function in C?

  • To print output to the screen (correct)
  • To perform arithmetic computations
  • To read input from the user
  • To declare variables

    • Which escape sequence in printf is used to start a new line?

  • \b
  • \r
  • \n (correct)
  • \t

    • What is the correct syntax to read an integer from the keyboard using scanf?

  • scanf('.d', &i);
  • scanf('%d', i);
  • scanf('%d', &i); (correct)
  • scanf('%i', &i);

    • What will happen if a variable is read before it has been assigned a value?

    <p>The variable will contain garbage data. (D)</p> Signup and view all the answers

    In mixed expressions, what happens to numbers when one of them is a float or double?

    <p>Everything is converted to double. (A)</p> Signup and view all the answers

    Which of the following is NOT a valid operator in C?

    <p>$ (D)</p> Signup and view all the answers

    What must be included in the program to use scanf and printf functions?

    <p>#include &lt;stdio.h&gt; (A)</p> Signup and view all the answers

    When performing division with integers in C, what will be the result?

    <p>An integer result (A)</p> Signup and view all the answers

    Flashcards

    printf function

    A C function used to display output on the screen.

    printf format specifiers

    Special characters like '%d' (integer), '%f' (float) used in printf to specify data types for printing.

    Type conversion in C

    C automatically adjusts data types during calculations involving both integers and floats. Floats usually take precedence.

    scanf function

    A C function for reading input from the keyboard.

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    scanf format specifiers

    Special sequences in scanf indicating data type expectations (e.g., '%d' for integers).

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    C Arithmetic Operators

    Symbols like +, -, *, / represent fundamental mathematical operations in C.

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    Variable Initialization

    Assigning a value to a variable before using it in a C program.

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    Integer Division

    C's division operator '/' returns integer results when both operands are integers.

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    Study Notes

    Variables and I/O

    • Today's Topics: Variables, input/output formats, arithmetic computations.

    Output - printf

    • printf: Used to display text and data on the screen.
    • printf is a family of functions, including fprint, vsprintf, sprintf, to print to files and variables.
    • Arguments: Specify what to print inside parentheses.
    • Format Specifiers: Use placeholders like %d (integers) and %f (floating-point numbers) within strings to display values from variables. Example string: "The value is %d", %d is replaced with an integer variable.
    • Multiple Output: Can print multiple variables in one printf statement

    printf Special Characters

    • \n: Newline
    • \r: Carriage return
    • \b: Backspace
      • \n: important when flushing the buffer, crucial for debugging

    Type Conversion and Arithmetic Operations

    • Combine different data types in expressions, result will be a double
    • Multiplying by 1.0 converts to a double, effectively changing the operation's type.
    • Converting data types may cause rounding. c = a + b, then d = c - a, d may not equal b due to rounding.

    Input - scanf

    • scanf: A function from the standard library to read input from the keyboard.
    • Syntax: It follows a similar format to printf using specifiers.
    • Pointers: Crucial: Input functions like scanf require pointers & to reference variables.

    Operators

    • Standard mathematical operators +, -, *, / are used.
    • Follow the usual mathematical order of operations..
    • Note that integer division results in an integer value.

    Initialization

    • Reading a variable before assigning a value might lead to unexpected results or errors (especially in larger programs).
    • Some compilers issue warnings for this potential problem (using flags, for example -W with GCC).

    math.h

    • math.h: A mathematical library providing standard functions.
    • Includes: Header file #include <math.h>
    • Constants: Predefined values like pi, e
    • Functions: Functions like log, sqrt, sin and so on.
    • Compilation: Needs a special compilation flag (-lm, for example) for the compiler to include math.h correctly.

    Conclusion

    • printf and scanf are necessary to communicate with the screen and keyboard.
    • Variable declaration must be done before use.
    • While spaces and tabs are not required by the compiler, they improve code readability.

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    Related Documents

    Programmeringsteknik DT143G Lecture 2: Variables and I/O PDF

    Description

    Explore the concepts of variables and input/output in C programming. Learn how to use the 'printf' function, format specifiers, and special characters for effective output. Additionally, understand type conversion and arithmetic computations in expressions.

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