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Summary - Conditionals

Combine if, switch and ternary to write a day-of-week app.

Summary - Conditionals

In this section you learned if, else if, else, switch, case, break, default and the ternary. Now we'll combine them in a day-of-week app.

The app takes a number (1-7) and prints the weekday. We'll do it first with if/else, then with switch; you'll see how both methods work.

Practice Write the day with if/else

Write a C program. Declare int day = 3;. With if (day == 1) print printf("Monday\n");, with else if (day == 2) print printf("Tuesday\n");, with else if (day == 3) print printf("Wednesday\n");, with else print printf("Other\n");. Put #include <stdio.h> at the top.

Starter code

main.c
#include <stdio.h>

int main(void) {
    // Declare day, print the day with if/else if/else
    return 0;
}

Sample solution

main.c
#include <stdio.h>

int main(void) {
    int day = 3;
    if (day == 1) {
        printf("Monday\n");
    } else if (day == 2) {
        printf("Tuesday\n");
    } else if (day == 3) {
        printf("Wednesday\n");
    } else {
        printf("Other\n");
    }
    return 0;
}

Expected output

Wednesday

Practice Write the day with switch

Write a C program. Declare int day = 3;. With switch (day) print case 1: printf("Monday\n"); break;, case 2: printf("Tuesday\n"); break;, case 3: printf("Wednesday\n"); break;, default: printf("Other\n");. Put #include <stdio.h> at the top.

Starter code

main.c
#include <stdio.h>

int main(void) {
    // Declare day, print the day with switch
    return 0;
}

Sample solution

main.c
#include <stdio.h>

int main(void) {
    int day = 3;
    switch (day) {
        case 1:
            printf("Monday\n");
            break;
        case 2:
            printf("Tuesday\n");
            break;
        case 3:
            printf("Wednesday\n");
            break;
        default:
            printf("Other\n");
    }
    return 0;
}

Expected output

Wednesday

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Which value type does switch work with?

main.c
switch (x) { case 1: ...; }
  • Only strings
  • Integer or char Correct answer
  • Floating-point
  • Arrays

Explanation: switch works only with integers or chars.

2 Even/odd with ternary

Question 
printf("%s
", (n % 2 == 0) ? "Even" : ____);
Answer 
printf("%s
", (n % 2 == 0) ? "Even" : "Odd");

Explanation: When false the string "Odd" is returned.

3 Match the condition statements

Term Meaning
if Single condition
else if Chained condition
switch Multi-way
? : One line

All lessons in Beginner

1 C basics

  1. What is C?
  2. Your first program
  3. Compile and run
  4. Comments
  5. printf and escapes
  6. Summary - C basics

2 Variables

  1. Declaring variables
  2. Variable assignment
  3. const
  4. Variable scope
  5. typedef
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. char
  4. sizeof
  5. Type conversion
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Menu loop
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Bitwise operators
  6. Summary - Operators

6 I/O

  1. printf formatting
  2. scanf
  3. Multiple inputs
  4. getchar and putchar
  5. puts and fputs
  6. Summary - I/O

7 Conditionals

  1. The if statement
  2. else and else if
  3. The switch statement
  4. The ternary operator
  5. Nested conditionals
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. break and continue
  5. Nested loops
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding products
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Array size
  4. Multidimensional arrays
  5. Arrays and loops
  6. Summary - Arrays

11 Strings

  1. String basics
  2. String literals
  3. strlen
  4. strcpy and strcat
  5. strcmp
  6. Summary - Strings

12 Functions

  1. Defining functions
  2. Return values
  3. Parameters
  4. Function prototypes
  5. Recursion
  6. Summary - Functions

13 Pointer basics

  1. What is a pointer?
  2. The & address operator
  3. Pointer dereference
  4. NULL
  5. Pointer arithmetic
  6. Summary - Pointer basics

14 Arrays and pointers

  1. Array name as pointer
  2. Pointer to array
  3. Passing arrays to functions
  4. Pointer loop
  5. Multidim array pointer
  6. Summary - Arrays and pointers

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String functions

  1. strchr
  2. strstr
  3. strtok
  4. sprintf
  5. sscanf
  6. Summary - String functions

17 Structs

  1. Defining structs
  2. Using structs
  3. typedef struct
  4. Array of structs
  5. Nested structs
  6. Summary - Structs

18 Memory and stack

  1. Stack and heap
  2. Automatic storage
  3. malloc
  4. free
  5. calloc and realloc
  6. Summary - Memory and stack

19 Preprocessor

  1. #define
  2. #include
  3. Conditional compilation
  4. Macro functions
  5. Header files
  6. Summary - Preprocessor

20 Beginner final

  1. Project design
  2. Data model
  3. Functions
  4. Memory management
  5. Putting it together